Organic electroluminescence device

ABSTRACT

An organic electroluminescence device includes an anode; a cathode; and at least one organic layer, which includes a light-emitting layer being provided between the anode and the cathode and containing at least one light-emitting material, and which contains at least one compound represented by formula (I): 
     
       
         
         
             
             
         
       
     
     wherein each of A 11 , A 12 , A 13 , A 14  and A 15  represents an N atom or C—R 11 , and the number of N atoms represented by A 11  to A 15  is 1 or 2; R 11  represents a hydrogen atom or a substituent, and at least one of R 11  represents an aryl group or an aromatic heterocyclic group; Q 11  represents a monocyclic aryl group or an aromatic heterocyclic group; R 12  represents an alkyl group; and each of n, m and l represents an integer of from 0 to 4, provided that n is 1 or more, n+m is 2 or more, and n+m+l is 4.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an organic electroluminescence device (hereinafter also referred to as “organic EL device”) capable of emitting light by converting electric energy to light.

2. Description of the Related Art

Since organic electroluminescence devices (organic EL devices) are capable of obtaining emission of light of high luminance by low voltage driving, they are actively researched and developed. An organic EL device generally comprises a pair of electrodes and an organic layer between the pair of electrodes, electrons injected from the cathode and holes injected from the anode are recombined in the organic layer, and generated energy of exciton is used for emission of light.

In recent years, increment in efficiency of devices has been advanced by the use of phosphorescent materials. As the phosphorescent materials, iridium complexes and platinum complexes are described in U.S. Pat. No. 6,303,238. However, devices that satisfy compatibility of high efficiency and high durability are not yet developed.

For the intention of obtaining materials of high durability, organic EL devices using a compound having an electron-defective nitrogen-containing heterocyclic group as the material are described in JP-A-2003-138251, JP-A-2004-103463 (The term “JP-A” as used herein refers to an “unexamined published Japanese patent application”.) and Chemistry of Materials, Vol. 10, pp. 3620-3625 (1998).

SUMMARY OF THE INVENTION

However, the materials used in these techniques have condensed rings, long in conjugated system, and low in the lowest excitation triplet (T₁ level) of molecules, so that these devices are susceptible to quenching of phosphorescence and luminous efficiency lowers. Further, materials high in T₁ level are low in electron affinity (Ea), and injection of electrons to the light-emitting layer and transportation are not sufficient, driving voltage of the devices and electric power consumption are high, so that luminous efficiency lowers. Accordingly, compatibility of high T₁ level and high Ea is not realized yet.

An object of the invention is to provide an organic electroluminescence device high in luminous efficiency and durability. Another object is to provide a silicon-linking type nitrogen-containing heterocyclic group compound suitable for use in the organic EL device.

As a result of earnest examinations by the present inventors to solve the above problems, it has been found that the above problems are dissolved by the use of an organic EL device containing a silicon-linking type nitrogen-containing heterocyclic group compound having a special structure in the organic layer. That is, the present invention has been achieved by the following means.

(1) An organic electroluminescence device comprising:

an anode;

a cathode; and

at least one organic layer,

wherein

the at least one organic layer comprises a light-emitting layer being provided between the anode and the cathode and containing at least one light-emitting material, and

the at least one organic layer contains at least one compound represented by formula (I):

wherein

each of A¹¹, A¹², A¹³, A⁴ and A¹⁵ represents an N atom or C—R¹¹, and the number of N atoms represented by A¹¹ to A¹⁵ is an integer of 1 or 2;

R¹¹ represents a hydrogen atom or a substituent, and at least one of R¹¹ represents an aryl group or an aromatic heterocyclic group;

when a plurality of partial structures represented by the following formula (I-a) are present, each partial structure (I-a) may be the same with or different from every other (I-a);

Q¹¹ represents a monocyclic aryl group or an aromatic heterocyclic group, and each Q¹¹ may be the same with or different from every other Q¹¹;

R¹² represents an alkyl group, and each R¹² may be the same with or different from every other R¹²; and

each of n, m and l represents an integer of from 0 to 4, provided that n is an integer of 1 or more, n+m is an integer of 2 or more, and n+m+l is 4:

(2) The organic electroluminescence device as described in (1), wherein

the compound represented by formula (I) is a compound represented by formula (II):

wherein

each of A²¹, A²² A²³, A²⁴ and A²⁵ represents an N atom or C—R²¹, and the number of N atom represented by A²¹ to A²⁵ is 1;

R²¹ represents a hydrogen atom or a substituent, and at least one of R²¹ represents an aryl group or an aromatic heterocyclic group;

when a plurality of partial structures represented by the following formula (II-a) are present, each partial structure (II-a) may be the same with or different from every other (II-a);

Q²¹ represents a monocyclic aryl group or an aromatic heterocyclic group, and each Q²¹ may be the same with or different from every other Q²¹;

R²² represents an alkyl group, and each R²² may be the same with or different from every other R²²; and

each of n, m and l represents an integer of from 0 to 4, provided that n is an integer of 1 or more, n+m is an integer of 2 or more, and n+m+l is 4:

(3) The organic electroluminescence device as described in (2), wherein

the compound represented by formula (II) is a compound represented by formula (III):

wherein

R³¹ represents a hydrogen atom or a substituent, and at least one of R³¹ represents an aryl group or an aromatic heterocyclic group;

when a plurality of partial structures represented by the following formula (III-a) are present, each partial structure (III-a) may be the same with or different from every other (III-a);

Q³¹ represents a monocyclic aryl group or an aromatic heterocyclic group, and each Q³¹ may be the same with or different from every other Q³¹;

R³² represents an alkyl group, and each R³² may be the same with or different from every other R³²; and

each of n, m and l represents an integer of from 0 to 4, provided that n is an integer of 1 or more, n+m is an integer of 2 or more, and n+m+l is 4:

(4) The organic electroluminescence device as described in (2), wherein

the compound represented by formula (II) is a compound represented by formula (IV):

wherein

R⁴¹ represents a hydrogen atom or a substituent, and at least one of R⁴¹ represents an aryl group or an aromatic heterocyclic group;

when a plurality of partial structures represented by the following formula (IV-a) are present, each partial structure (IV-a) may be the same with or different from every other (IV-a);

Q⁴¹ represents a monocyclic aryl group or an aromatic heterocyclic group, and each Q⁴¹ may be the same with or different from every other Q⁴¹;

R⁴² represents an alkyl group, and each R⁴² may be the same with or different from every other R⁴²; and

each of n, m and l represents an integer of from 0 to 4, provided that n is an integer of 1 or more, n+m is an integer of 2 or more, and n+m+l is 4:

(5) The organic electroluminescence device as described in (2), wherein

the compound represented by formula (II) is a compound represented by formula (V):

wherein

R⁵¹ represents a hydrogen atom or a substituent, and at least one of R⁵¹ represents an aryl group or an aromatic heterocyclic group;

when a plurality of partial structures represented by the following formula (V-a) are present, each partial structure (V-a) may be the same with or different from every other (V-a);

Q⁵¹ represents a monocyclic aryl group or an aromatic heterocyclic group, and each Q⁵¹ may be the same with or different from every other Q⁵¹;

R⁵² represents an alkyl group, and each R⁵² may be the same with or different from every other R⁵²; and

each of n, m and l represents an integer of from 0 to 4, provided that n is an integer of 1 or more, n+m is an integer of 2 or more, and n+m+l is 4:

(6) The organic electroluminescence device as described in (1), wherein the compound represented by formula (I) has a glass transition temperature of 130° C. or more and 450° C. or less. (7) The organic electroluminescence device as described in (1), wherein

the compound represented by formula (I) has a lowest excitation triplet energy level of 65 kcal/mol (272.35 kJ/mol) or more and 95 kcal/mol (398.05 kJ/mol) or less.

(8) The organic electroluminescence device as described in (1), wherein

the at least one light-emitting material comprises a phosphorescent material.

(9) The organic electroluminescence device as described in (8), wherein

the phosphorescent material is an iridium complex or a platinum complex.

(10) The organic electroluminescence device as described in (9), wherein the platinum complex is a platinum complex represented by formula (Cal):

wherein

each of Q¹, Q², Q³ and Q⁴ independently represents a ligand to coordinate to Pt; and

each of L¹, L² and L³ independently represents a single bond or a divalent linking group.

(11) The organic electroluminescence device as described in (1), wherein

the light-emitting layer contains the compound represented by formula (I).

(12) The organic electroluminescence device as described in (1), wherein

the at least one organic layer further comprises at least one electron transporting layer being provided between the light-emitting layer and the cathode, and

the at least one electron transporting layer contains the compound represented by formula (I).

DETAILED DESCRIPTION OF THE INVENTION

The organic electroluminescence device in the invention is an organic electroluminescence device comprising an anode; a cathode; and at least one organic layer, wherein the at least one organic layer comprises a light-emitting layer being provided between the anode and the cathode and containing at least one light-emitting material, and the at least one organic layer contains at least one compound represented by formula (I):

In formula (I), each of A¹¹, A¹², A¹³, A¹⁴ and A¹⁵ represents an N atom or C—R¹¹, and the number of N atoms represented by A¹¹ to A¹⁵ is an integer of 1 or 2; R¹¹ represents a hydrogen atom or a substituent, and at least one of R¹¹ represents an aryl group or an aromatic heterocyclic group, when a plurality of partial structures represented by the following formula (I-a) are present, each partial structure (I-a) may be the same with or different from every other (I-a); Q¹¹ represents a monocyclic aryl group or an aromatic heterocyclic group, and each Q¹¹ may be the same with or different from every other Q¹¹; R¹² represents an alkyl group, and each R¹² may be the same with or different from every other R¹²; and each of n, m and l represents an integer of from 0 to 4, provided that n is an integer of 1 or more, n+m is an integer of 2 or more, and n+m+l is 4.

That is, the organic electroluminescence device in the invention has at least one organic light-emitting layer (the light-emitting layer). Further, as the organic layers other than the light-emitting layer, a hole injecting layer, a hole transporting layer, an electron-blocking layer, an exciton-blocking layer, a hole-blocking layer, an electron transporting layer, an electron injecting layer, and a protective layer may be arbitrarily arranged, and each layer may unite functions of other layers. Further, each layer may be composed of a plurality of layers.

The organic electroluminescence device in the invention may be the one utilizing emission of light from excitation singlet (fluorescence), or may be the one utilizing emission of light from excitation triplet (phosphorescence), but the one using phosphorescence is preferred from the viewpoint of luminous efficiency.

The light-emitting layer of the organic electroluminescence device in the invention is preferably composed of at least one light-emitting material and at least one host material. Here, the host material means a material other than the light-emitting material of the materials constituting the light-emitting layer, which has at least one function of a function of dispersing a light-emitting material and maintaining the dispersion in the light-emitting layer, a function of receiving holes from the anode and a hole transporting layer, a function of receiving electrons from the cathode and an electron transporting layer, a function of transporting at least one of holes and electrons, a function of offering the place of recombination of holes and electrons, a function of transporting the energy of exciton generated by the recombination to the light-emitting material, and a function of transporting at least one of holes and electrons to the light-emitting material.

The compounds of the invention may be contained in any layer of the organic layers, and may be contained in a plurality of layers, but they are preferably contained in a light-emitting layer, a hole blocking layer, an electron transporting layer, or an electron injecting layer, more preferably contained in a light-emitting layer, or an electron transporting layer, still more preferably contained in a light-emitting layer, and most preferably contained in a light-emitting layer as host materials. When the compounds of the invention are contained in a light-emitting layer as host materials, the content of the compounds of the invention in the light-emitting layer is preferably from 50 to 99.9 mass %, and more preferably from 60 to 99 mass %. Further, when the compounds of the invention are contained in a hole blocking layer, an electron transporting layer, or an electron injecting layer, the content of the compounds of the invention in each layer is preferably from 70 to 100%, more preferably from 85 to 100%, and most preferably from 99 to 100%. Further, when an electron transporting layer consists of two or more layers, it is sufficient for any one layer to contain the compounds of the invention.

The compound represented by formula (I) will be explained in detail below.

In formula (I), each of A¹¹, A¹², A¹³, A¹⁴ and A¹⁵ represents an N atom or C—R¹¹, and the number of N atoms represented by A¹¹ to A¹⁵ is an integer of 1 or 2. R¹¹ represents a hydrogen atom or a substituent, and at least one of R¹¹ represents an aryl group or an aromatic heterocyclic group. When there are present a plurality of partial structures represented by the following formula (I-a), each partial structure (I-a) may be the same with or different from every other (I-a). Q¹¹ represents a monocyclic aryl group or an aromatic heterocyclic group, and each Q¹¹ may be the same with or different from every other Q¹¹. R¹² represents an alkyl group, and each R¹² may be the same with or different from every other R¹². Each of n, m and l represents an integer of from 0 to 4, provided that n is an integer of l or more, n+m is an integer of 2 or more, and n+m+l is 4.

Formula (I) is described below. Each of A¹¹ to A¹⁵ represents an N atom or C—R¹¹, and the number of N atoms represented by A¹¹ to A¹⁵ is an integer of 1 or 2, and the position thereof is not especially restricted. R¹¹ represents a hydrogen atom or a substituent, and at least one of R¹¹ represents an aryl group or an aromatic heterocyclic group. Each R¹¹ may be the same with or different from every other R¹¹. Further, a plurality of R¹¹ are not linked to each other to form a condensed ring. As the examples of the substituents represented by R¹¹, substituent group A described below is applicable to the substituents.

Substituent Group A:

An alkyl group (preferably having from 1 to 30 carbon atoms, more preferably from 1 to 20 carbon atoms, and especially preferably from 1 to 10 carbon atoms, e.g., methyl, ethyl, isopropyl, tert-butyl, n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc., are exemplified), an alkenyl group (preferably having from 2 to 30 carbon atoms, more preferably from 2 to 20 carbon atoms, and especially preferably from 2 to 10 carbon atoms, e.g., vinyl, allyl, 2-butenyl, 3-pentenyl, etc., are exemplified), an alkynyl group (preferably having from 2 to 30 carbon atoms, more preferably from 2 to 20 carbon atoms, and especially preferably from 2 to 10 carbon atoms, e.g., propargyl, 3-pentynyl, etc., are exemplified), an aryl group (preferably having from 6 to 30 carbon atoms, more preferably from 6 to 20 carbon atoms, and especially preferably from 6 to 12 carbon atoms, e.g., phenyl, p-methylphenyl, naphthyl, anthranyl, etc., are exemplified), an amino group (preferably having from 0 to 30 carbon atoms, more preferably from 0 to 20 carbon atoms, and especially preferably from 0 to 10 carbon atoms, e.g., amino, methylamino, dimethylamino, diethylamino, dibenzylamino, diphenylamino, ditolylamino, etc., are exemplified), an alkoxy group (preferably having from 1 to 30 carbon atoms, more preferably from 1 to 20 carbon atoms, and especially preferably from 1 to 10 carbon atoms, e.g., methoxy, ethoxy, butoxy, 2-ethylhexyloxy, etc., are exemplified), an aryloxy group (preferably having from 6 to 30 carbon atoms, more preferably from 6 to 20 carbon atoms, and especially preferably from 6 to 12 carbon atoms, e.g., phenyloxy, 1-naphthyloxy, 2-naphthyloxy, etc., are exemplified), a heterocyclic oxy group (preferably having from 1 to 30 carbon atoms, more preferably from 1 to 20 carbon atoms, and especially preferably from 1 to 12 carbon atoms, e.g., pyridyloxy, pyrazyloxy, pyrimidyloxy, quinolyloxy, etc., are exemplified), an acyl group (preferably having from 2 to 30 carbon atoms, more preferably from 2 to 20 carbon atoms, and especially preferably from 2 to 12 carbon atoms, e.g., acetyl, benzoyl, formyl, pivaloyl, etc., are exemplified), an alkoxycarbonyl group (preferably having from 2 to 30 carbon atoms, more preferably from 2 to 20 carbon atoms, and especially preferably from 2 to 12 carbon atoms, e.g., methoxycarbonyl, ethoxycarbonyl, etc., are exemplified), an aryloxycarbonyl group (preferably having from 7 to 30 carbon atoms, more preferably from 7 to 20 carbon atoms, and especially preferably from 7 to 12 carbon atoms, e.g., phenyloxycarbonyl, etc., are exemplified), an acyloxy group (preferably having from 2 to 30 carbon atoms, more preferably from 2 to 20 carbon atoms, and especially preferably from 2 to 10 carbon atoms, e.g., acetoxy, benzoyloxy, etc., are exemplified), an acylamino group (preferably having from 2 to 30 carbon atoms, more preferably from 2 to 20 carbon atoms, and especially preferably from 2 to 10 carbon atoms, e.g., acetylamino, benzoylamino, etc., are exemplified), an alkoxycarbonylamino group (preferably having from 2 to 30 carbon atoms, more preferably from 2 to 20 carbon atoms, and especially preferably from 2 to 12 carbon atoms, e.g., methoxycarbonylamino, etc., are exemplified), an aryloxycarbonylamino group (preferably having from 7 to 30 carbon atoms, more preferably from 7 to 20 carbon atoms, and especially preferably from 7 to 12 carbon atoms, e.g., phenyloxycarbonylamino, etc., are exemplified), a sulfonylamino group (preferably having from 1 to 30 carbon atoms, more preferably from 1 to 20 carbon atoms, and especially preferably from 1 to 12 carbon atoms, e.g., methanesulfonylamino, benzenesulfonylamino, etc., are exemplified), a sulfamoyl group (preferably having from 0 to 30 carbon atoms, more preferably from 0 to 20 carbon atoms, and especially preferably from 0 to 12 carbon atoms, e.g., sulfamoyl, methylsulfamoyl, dimethylsulfamoyl, phenylsulfamoyl, etc., are exemplified), a carbamoyl group (preferably having from 1 to 30 carbon atoms, more preferably from 1 to 20 carbon atoms, and especially preferably from 1 to 12 carbon atoms, e.g., carbamoyl, methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl, etc., are exemplified), an alkylthio group (preferably having from 1 to 30 carbon atoms, more preferably from 1 to 20 carbon atoms, and especially preferably from 1 to 12 carbon atoms, e.g., methylthio, ethylthio, etc., are exemplified), an arylthio group (preferably having from 6 to 30 carbon atoms, more preferably from 6 to 20 carbon atoms, and especially preferably from 6 to 12 carbon atoms, e.g., phenylthio, etc., are exemplified), a heterocyclic thio group (preferably having from 1 to 30 carbon atoms, more preferably from 1 to 20 carbon atoms, and especially preferably from 1 to 12 carbon atoms, e.g., pyridylthio, 2-benzimizolylthio, 2-benzoxazolylthio, 2-benzothiazolylthio, etc., are exemplified), a sulfonyl group (preferably having from 1 to 30 carbon atoms, more preferably from 1 to 20 carbon atoms, and especially preferably from 1 to 12 carbon atoms, e.g., mesyl, tosyl, etc., are exemplified), a sulfinyl group (preferably having from 1 to 30 carbon atoms, more preferably from 1 to 20 carbon atoms, and especially preferably from 1 to 12 carbon atoms, e.g., methanesulfinyl, benzenesulfinyl, etc., are exemplified), a ureido group (preferably having from 1 to 30 carbon atoms, more preferably from 1 to 20 carbon atoms, and especially preferably from 1 to 12 carbon atoms, e.g., ureido, methylureido, phenylureido, etc., are exemplified), a phosphoric acid amido group (preferably having from 1 to 30 carbon atoms, more preferably from 1 to 20 carbon atoms, and especially preferably from 1 to 12 carbon atoms, e.g., diethylphosphoric acid amido, phenylphosphoric acid amido, etc., are exemplified), a hydroxyl group, a mercapto group, a halogen atom (e.g., a fluorine atom, a chlorine atom, a bromine atom, an iodine atom), a cyano group, a sulfo group, a carboxyl group, a nitro group, a hydroxamic acid group, a sulfino group, a hydrazino group, an imino group, a heterocyclic group (also including an aromatic heterocyclic group, preferably having from 1 to 30 carbon atoms, and more preferably from 1 to 12 carbon atoms, and as the hetero atoms, e.g., a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, a silicon atom, a selenium atom, and a tellurium atom are exemplified, specifically, e.g., pyridyl, pyrazinyl, pyrimidyl, pyridazinyl, pyrrolyl, pyrazolyl, triazolyl, imidazolyl, oxazolyl, thiazolyl, isoxazolyl, isothiazolyl, quinolyl, furyl, thienyl, selenophenyl, tellurophenyl, piperidyl, piperidino, morpholino, pyrrolidyl, pyrrolidino, benzoxazolyl, benzimidazolyl, benzothiazolyl, a carbazolyl group, an azepinyl group, a silolyl group, etc., are exemplified), a silyl group (preferably having from 3 to 40 carbon atoms, more preferably from 3 to 30 carbon atoms, and especially preferably from 3 to 24 carbon atoms, e.g., trimethylsilyl, triphenylsilyl, etc., are exemplified), a silyloxy group (preferably having from 3 to 40 carbon atoms, more preferably from 3 to 30 carbon atoms, and especially preferably from 3 to 24 carbon atoms, e.g., trimethylsilyloxy, triphenylsilyloxy, etc., are exemplified), and a phosphoryl group (e.g., a diphenylphosphoryl group, a dimethylphosphoryl group, etc., are exemplified) are exemplified. These substituents may further be substituted, and the substituents selected from substituent group A described above can be exemplified as further substituents.

Each R¹¹ may be the same with or different from every other R¹¹. R¹¹ may further have a substituent, and substituent group A is applicable to the substituent.

The substituents represented by R¹¹ are preferably a hydrogen atom, an alkyl group, an aryl group, a fluorine group, an amino group, an alkoxy group, an aryloxy group, a heterocyclic oxy group, an alkylthio group, an arylthio group, a heterocyclic thio group, a cyano group, a heterocyclic group, a silyl group, and a silyloxy group, more preferably a hydrogen atom, an alkyl group, an aryl group, a fluorine group, a cyano group, a silyl group, and a heterocyclic group, still more preferably a hydrogen atom, an alkyl group, an aryl group, a fluorine group, a cyano group, a silyl group, and a heterocyclic group, and especially preferably a hydrogen atom, an alkyl group, an aryl group, and a heterocyclic group. These substituents are preferred for capable of improving chemical and thermal stability of the compound represented by formula (I).

The ring of at least one aryl group or aromatic heterocyclic group contained in R¹¹ is not especially restricted, but is preferably a 4- to 10-membered ring, more preferably a 5- to 7-membered ring, still more preferably a 5- or 6-membered ring, and especially preferably a 6-membered ring. The hetero atoms contained in the aromatic heterocyclic ring are not especially restricted, but an aromatic heterocyclic ring containing nitrogen, oxygen, sulfur, selenium, silicon, germanium or phosphorus is preferred, nitrogen, oxygen or sulfur is more preferred, nitrogen or oxygen is still more preferred, and nitrogen is especially preferred. The number of hetero atoms contained in one aromatic heterocyclic ring is not especially restricted, but is preferably from 1 to 3.

The specific examples of the rings of at least one aryl group or aromatic heterocyclic group contained in R¹¹ include a benzene ring group, a pyridine ring group, a pyrazine ring group, a pyrimidine ring group, a triazine ring group, a pyridazine ring group, a pyrrole ring group, a pyrazole ring group, an imidazole ring group, a triazole ring group, an oxazole ring group, an oxadiazole ring group, a thiazole ring group, a thiadiazole ring group, a furan ring group, a thiophene ring group, a selenophene ring group, a silol ring group, a germole ring group, and a phosphole ring group. The above substituents may further have a substituent.

The preferred examples of the rings of at least one aryl group or aromatic heterocyclic group contained in R¹¹ include a benzene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazine ring, a pyrrole ring, a pyrazole ring, an imidazole ring, a triazole ring, an oxazole ring, a thiazole ring, a furan ring, and a thiophene ring, more preferably a benzene ring, a pyridine ring, a pyrazine ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxazole ring, a thiazole ring, and a thiophene ring, still more preferably a benzene ring, a pyridine ring, a pyrazine ring, a pyrazole ring, an imidazole ring, and a thiophene ring, and especially preferably a benzene ring, a pyridine ring, and a pyrazine ring.

The ring of the monocyclic aryl group or aromatic heterocyclic group represented by Q¹¹ is not especially restricted, but from the aspects of maintaining chemical stability and high excitation triplet energy level, a 4- to 10-membered ring is preferred, a 5- to 7-membered ring is more preferred, a 5- or 6-membered ring is still more preferred, and a 6-membered ring is especially preferred. The hetero atoms contained in the ring of the aromatic heterocyclic group represented by Q¹¹ are not especially restricted, but an aromatic heterocyclic ring containing nitrogen, oxygen, sulfur, selenium, silicon, germanium or phosphorus is preferred, nitrogen, oxygen or sulfur is more preferred, nitrogen or oxygen is still more preferred, and nitrogen is especially preferred. The number of hetero atoms contained in one aromatic heterocyclic ring is not especially restricted, but the number of from 1 to 3 is preferred.

The specific examples of the rings of the monocyclic aryl group or aromatic heterocyclic group represented by Q¹¹ include a benzene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazine ring, a pyridazine ring, a pyrrole ring, a pyrazole ring, an imidazole ring, a triazole ring, an oxazole ring, an oxadiazole ring, a thiazole ring, a thiadiazole ring, a furan ring, a thiophene ring, a selenophene ring, a silol ring, a germole ring, and a phosphole ring.

The aryl group or aromatic heterocyclic group formed of Q¹¹ may have a substituent, and substituent group A described above is applicable to the substituents, However, an aryl ring or an aromatic heterocyclic ring is not substituted.

The rings of the monocyclic aryl group or aromatic heterocyclic group represented by Q¹¹ include preferably a benzene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazine ring, a pyridazine ring, a pyrrole ring, a pyrazole ring, an imidazole ring, a triazole ring, an oxazole ring, an oxadiazole ring, a thiazole ring, a thiadiazole ring, a furan ring, a thiophene ring, a selenophene ring, a silol ring, a germole ring, and a phosphole ring, more preferably a benzene ring, a pyridine ring, a pyrazine ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxazole ring, a thiazole ring, and a thiadiazole ring, still more preferably a benzene ring, a pyridine ring, a pyrazine ring, a pyrazole ring, an imidazole ring, and a thiadiazole ring, and especially preferably a benzene ring, a pyridine ring and a pyrazine ring.

The alkyl group represented by R¹² may further have a substituent, and substituent group A described above is applicable to the substituent. Each R¹² may be the same with or different from every other R¹². Since the alkyl group represented by R¹² does not contribute to electron transportation in the EL device, 1 that represents the number of substitution of R¹² is preferably zero.

As one of the preferred embodiments in the light of the improvement of chemical stability, the compound represented by formula (I) is a compound represented by the following formula (II).

In formula (II), each of A²¹, A²², A²³, A²⁴ and A²⁵ represents an N atom or C—R²¹, and the number of N atom represented by A²¹ to A²⁵ is 1. R²¹ represents a hydrogen atom or a substituent. At least one of R²¹ represents an aryl group or an aromatic heterocyclic group. When there are present a plurality of partial structures represented by the following formula (II-a), each partial structure (II-a) may be the same with or different from every other (II-a). Q²¹ represents a monocyclic aryl group or an aromatic heterocyclic group. Each Q²¹ may be the same with or different from every other Q²¹. R²² represents an alkyl group. Each R²² may be the same with or different from every other R²². Each of n, m and l represents an integer of from 0 to 4, provided that n is an integer of 1 or more, n+m is an integer of 2 or more, and n+m+l is 4.

Formula (II) is described below. A²¹ to A²⁵, R²¹, R²², Q²¹, n, m and l respectively have the same meanings as A¹¹ to A¹⁵, R¹¹, R¹², Q¹¹, n, m and l in formula (I), and preferred ranges are also the same.

The compound represented by formula (II) is more preferably a compound represented by formula (III), (IV) or (V) in view of the improvement of chemical stability.

In formula (III), R³¹ represents a hydrogen atom or a substituent. At least one of R³¹ represents an aryl group or an aromatic heterocyclic group. When there are present a plurality of partial structures represented by the following formula (III-a), each partial structure (III-a) may be the same with or different from every other (III-a). Q³¹ represents a monocyclic aryl group or an aromatic heterocyclic group. Each Q³¹ may be the same with or different from every other Q³¹. R³² represents an alkyl group. Each R³² may be the same with or different from every other R³². Each of n, m and l represents an integer of from 0 to 4, provided that n is an integer of 1 or more, n+m is an integer of 2 or more, and n+m+l is 4.

Formula (III) is described below. R³¹, R³², Q³¹, n, m and l respectively have the same meanings as R²¹, R²², Q²¹, n, m and l in formula (II), and preferred ranges are also the same.

For maintaining high excitation triplet energy level, the compound represented by formula (III) is more preferably a compound represented by the following formula (III-b).

In formula (III-b), R¹¹ represents a hydrogen atom or a substituent. At least one of R³¹ represents an aryl group or an aromatic heterocyclic group. When there are present a plurality of partial structures represented by the following formula (III-b)′, each partial structure (III-b)′ may be the same with or different from every other (III-b)′. Q³¹ represents a monocyclic aryl group or an aromatic heterocyclic group. Each Q³¹ may be the same with or different from every other Q³¹. Q³² represents an aryl group or an aromatic heterocyclic group. R³² represents an alkyl group. Each R³² may be the same with or different from every other R³². Each of n, m and l represents an integer of from 0 to 4, provided that n is an integer of 1 or more, n+m is an integer of 2 or more, and n+m+l is 4.

Formula (III-b) is described below. R³¹, R³², Q³¹, n, m and l respectively have the same meanings as R³¹, R³², Q³¹, n, m and l in formula (III), and preferred ranges are also the same.

The ring of the aryl group or aromatic heterocyclic group represented by Q³² is not especially restricted, but from the aspects of maintaining chemical stability and high excitation triplet energy level, a 4- to 10-membered ring is preferred, a 5- to 7-membered ring is more preferred, a 5- or 6-membered ring is still more preferred, and a 6-membered ring is especially preferred. The hetero atoms contained in the aromatic heterocyclic ring represented by Q³² are not especially restricted, but an aromatic heterocyclic ring containing nitrogen, oxygen, sulfur, selenium, silicon, germanium or phosphorus is preferred, nitrogen, oxygen or sulfur is more preferred, nitrogen or oxygen is still more preferred, and nitrogen is especially preferred. The number of hetero atoms contained in one aromatic heterocyclic ring is not especially restricted, but the number of from 1 to 3 is preferred.

The specific examples of the rings of the aryl group or aromatic heterocyclic group represented by Q³² include a benzene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazine ring, a pyridazine ring, a pyrrole ring, a pyrazole ring, an imidazole ring, a triazole ring, an oxazole ring, an oxadiazole ring, a thiazole ring, a thiadiazole ring, a furan ring, a thiophene ring, a selenophene ring, a silol ring, a germole ring, and a phosphole ring.

The aryl group or aromatic heterocyclic group formed of Q³² may have a substituent, and substituent group A described above is applicable to the substituents.

The rings of the aryl group or aromatic heterocyclic group represented by Q³² include preferably a benzene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazine ring, a pyridazine ring, a pyrrole ring, a pyrazole ring, an imidazole ring, a triazole ring, an oxazole ring, an oxadiazole ring, a thiazole ring, a thiadiazole ring, a furan ring, a thiophene ring, a selenophene ring, a silol ring, a germole ring, and a phosphole ring, more preferably a benzene ring, a pyridine ring, a pyrazine ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxazole ring, a thiazole ring, and a thiadiazole ring, still more preferably a benzene ring, a pyridine ring, a pyrazine ring, a pyrazole ring, an imidazole ring, and a thiadiazole ring, and especially preferably a benzene ring, a pyridine ring and a pyrazine ring.

In formula (IV), R⁴¹ represents a hydrogen atom or a substituent. At least one of R⁴¹ represents an aryl group or an aromatic heterocyclic group. When there are present a plurality of partial structures represented by the following formula (IV-a), each partial structure (IV-a) may be the same with or different from every other (IV-a). Q⁴¹ represents a monocyclic aryl group or an aromatic heterocyclic group. Each Q⁴¹ may be the same with or different from every other Q⁴¹. R⁴² represents an alkyl group. Each R⁴² may be the same with or different from every other R⁴². Each of n, m and l represents an integer of from 0 to 4, provided that n is an integer of 1 or more, n+m is an integer of 2 or more, and n+m+l is 4.

In formula (IV), R⁴¹, R⁴², Q⁴¹, n, m and l respectively have the same meanings as R²¹, R²², Q²¹, n, m and l in formula (II), and preferred ranges are also the same.

For maintaining high excitation triplet energy level, the compound represented by formula (IV) is more preferably a compound represented by the following formula (IV-b).

In formula (IV-b), R⁴¹ represents a hydrogen atom or a substituent. At least one of R⁴¹ represents an aryl group or an aromatic heterocyclic group. When there are present a plurality of partial structures represented by the following formula (IV-b)′, each partial structure (IV-b)′ may be the same with or different from every other (IV-b)′. Q⁴¹ represents a monocyclic aryl group or an aromatic heterocyclic group. Each Q⁴¹ may be the same with or different from every other Q⁴¹. Q⁴² represents an aryl group or an aromatic heterocyclic group. R⁴² represents an alkyl group. Each R⁴² may be the same with or different from every other R⁴². Each of n, m and l represents an integer of from 0 to 4, provided that n is an integer of 1 or more, n+m is an integer of 2 or more, and n+m+l is 4.

Formula (IV-b) is described below. R⁴¹, R⁴², Q⁴¹, n, m and l respectively have the same meanings as R²¹, R²², Q²¹, n, m and l in formula (II), and preferred ranges are also the same, Q⁴² has the same meaning as Q³² in formula (III-b), and a preferred range is also the same.

In formula (V), R⁵¹ represents a hydrogen atom or a substituent. At least one of R⁵¹ represents an aryl group or an aromatic heterocyclic group. When there are present a plurality of partial structures represented by the following formula (V-a), each partial structure (V-a) may be the same with or different from every other (V-a). Q⁵¹ represents a monocyclic aryl group or an aromatic heterocyclic group. Each Q⁵¹ may be the same with or different from every other Q⁵¹. R⁵² represents an alkyl group. Each R⁵² may be the same with or different from every other R⁵². Each of n, m and l represents an integer of from 0 to 4, provided that n is an integer of 1 or more, n+m is an integer of 2 or more, and n+m+l is 4.

Formula (V) is described below. R⁵¹, R⁵², QS, n, m and l respectively have the same meanings as R²¹, R²², Q²¹, n, m and l in formula (II), and preferred ranges are also the same.

For maintaining high excitation triplet energy level, the compound represented by formula (V) is more preferably a compound represented by the following formula (V-b).

In formula (V-b), R⁵¹ represents a hydrogen atom or a substituent. At least one of R⁵¹ represents an aryl group or an aromatic heterocyclic group. When there are present a plurality of partial structures represented by the following formula (V-b)′, each partial structure (V-b)′ may be the same with or different from every other (V-b)′. Q⁵¹ represents a monocyclic aryl group or an aromatic heterocyclic group. Each Q⁵¹ may be the same with or different from every other Q⁵¹. Q⁵² represents an aryl group or an aromatic heterocyclic group. R⁵² represents an alkyl group. Each R⁵² may be the same with or different from every other R⁵². Each of n, m and l represents an integer of from 0 to 4, provided that n is an integer of 1 or more, n+m is an integer of 2 or more, and n+m+l is 4.

Formula (V-b) is described below. R⁵¹, R⁵², Q⁵¹, n, m and l respectively have the same meanings as R²¹, R²², Q²¹, n, m and l in formula (II), and preferred ranges are also the same. Q⁵² has the same meaning as Q³² in formula (III-b), and a preferred range is also the same.

The compound represented by formula (I) of the invention may be a low molecular weight compound, or may be a polymer compound having a residue structure linking to the polymer main chain (preferably having a mass average molecular weight of from 1,000 to 5,000,000, more preferably from 5,000 to 2,000,000, and still more preferably from 10,000 to 1,000,000), or may be a polymer compound having the structure of the compound represented by formula (I) in the main chain (preferably having a mass average molecular weight of from 1,000 to 5,000,000, more preferably from 5,000 to 2,000,000, and still more preferably from 10,000 to 1,000,000). In the case of a polymer compound, it may be a homopolymer, or may be a copolymer with other polymer, and in the case of a copolymer, it may be a random copolymer, or may be a block copolymer. Furthers in the case of a copolymer, at least one of a compound having a light emitting function and a compound having a charge transporting may be contained in the polymer.

The specific examples of the compounds represented by formula (I), (II), (III), (IV) or (V) are shown below, but the invention is not restricted to these compounds. (Incidentally in the present specification, Ph means a phenyl group, and ^(t)Bu means a tertiary butyl group.)

The compounds represented by any of formulae (I) to (V) of the invention can be synthesized according to various well-known synthesizing methods.

The specific synthesizing prescriptions are described in the Examples below.

Considering the driving durability of the device, the glass transition temperature (Tg) of the compound of the invention is preferably 130° C. or more and 450° C. or less, more preferably 135° C. or more and 450° C. or less, still more preferably 140° C. or more and 450° C. or less, especially preferably 150° C. or more and 450° C. or less, and most preferably 160° C. or more and 450° C. or less.

Here, Tg can be confirmed by thermal measurement such as differential scanning calorimetry (DSC) and differential thermal analysis (DTA), X-ray diffraction (XRD), and observation with a polarization microscope. Measurement of Tg by differential scanning calorimetry (DSC) is especially preferred.

When the device of the invention is a luminescence device utilizing phosphorescence, the lowest excitation triplet energy (T₁ energy) of the compound of the invention is preferably 64 kcal/mol (272.35 kJ/mol) or more and 95 kcal/mol (398.05 kJ/mol) or less, more preferably 67 kcal/mol (280.73 kJ/mol) or more and 95 kcal/mol (398.05 kJ/mol) or less, and still more preferably 69 kcal/mol (289.11 kJ/mol) or more and 95 kcal/mol (398.05 kJ/mol) or less.

Here, T₁ level can be found by measuring the spectrum of phosphorescence of the film of a material, and from the short wave end of the spectrum of phosphorescence. For example, T₁ level of Exemplified Compound 91 is 64 kcal/mol, and T₁ level of Exemplified Compound 116 is 74 kcal/mol.

Organic Electroluminescence Device:

It is preferred for the organic electroluminescence device to have at least one electron transporting layer between the light-emitting layer and the cathode, wherein the at least one electron transporting layer contains the compound represented by formulae (I)

The organic electroluminescence device in the invention comprises a substrate having thereon the cathode and the anode and an organic layer including a light-emitting layer between the electrodes. It is preferred that at least one electrode of the cathode and the anode is transparent from the properties of the luminescence device.

As the form of lamination of the organic layers in the invention, an embodiment of lamination of a hole-transporting layer, a light-emitting layer and an electron-transporting layer from the anode side is preferred. Further, a hole-injecting layer is provided between the hole-transporting layer and the anode, and/or an electron-transporting intermediate layer is provided between the light-emitting layer and the electron-transporting layer. In addition, it is also possible to provide a hole-transporting intermediate layer between the light-emitting layer and the hole-transporting layer and an electron-injecting layer between the cathode and the electron-transporting layer

Incidentally, each of these layers may consist of a plurality of layers.

Each layer constituting the organic layers can be preferably formed by any of dry film-forming methods such as a vacuum deposition method or a sputtering method, a transfer method, a printing method, a coating method, an ink jet method, and a spraying method.

The elements constituting the luminescence device of the invention will be described in detail below.

Substrate:

The substrate for use in the invention is preferably a substrate that does not scatter or attenuate the light emitted from the organic layers. The specific examples of the materials of the substrate include inorganic materials, e.g., yttria stabilized zirconia (YSZ), glass, etc., and organic materials, such as polyester, e.g., polyethylene terephthalate, polybutylene phthalate, polyethylene naphthalate, etc., polystyrene, polycarbonate, polyether sulfone, polyallylate, polyimide, polycycloolefin, norbornene resin, poly(chlorotrifluoroethylene), etc.

When glass is used as the substrate, non-alkali glass is preferably used as the material for reducing elution of ions from the glass. Further, when soda lime glass is used, it is preferred to provide a barrier coat such as silica. In the case of organic materials, materials excellent in heat resistance, dimensional stability, solvent resistance, electrical insulating properties and processability are preferably used.

The shape, structure and size of the substrate are not especially restricted, and these can be arbitrarily selected in accordance with the intended use and purpose of the luminescent device. In general, the substrate is preferably plate-shaped. The structure of the substrate may be a single layer structure or may be a lamination structure, and may consist of a single member or may be formed of two or more members.

The substrate may be colorless and transparent, or may be colored and transparent, but from the point of not scattering or attenuating the light emitted from the organic light-emitting layer, a colorless and transparent substrate is preferably used.

The substrate can be provided with a moisture permeation preventing layer (a gas barrier layer) on the front surface or rear surface.

As the materials of the moisture permeation-preventing layer (the gas barrier layer), inorganic materials such as silicon nitride and silicon oxide are preferably used. The moisture permeation-preventing layer (the gas barrier layer) can be formed, for example, by a high frequency sputtering method.

When a thermoplastic substrate is used, if necessary, a hard coat layer and an undercoat layer may further be provided.

Anode:

The anode is generally sufficient to have the function of the electrode to supply holes to an organic layer. The shape, structure and size of the anode are not especially restricted, and these can be arbitrarily selected from known materials of electrode in accordance with the intended use and purpose of the luminescent device. The anode is generally provided as the transparent anode.

As the materials of anode, for example, metals, alloys, metallic oxides, electrically conductive compounds, and mixtures of these materials are preferably exemplified. The specific examples of the materials of anode include electrically conductive metallic oxides, e.g., tin oxides doped with antimony or fluorine (ATO, FTO), tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), etc., metals, e.g., gold, silver, chromium, nickel, etc., mixtures or laminates of these metals with electrically conductive metallic oxides, inorganic electrically conductive substances, e.g., copper iodide, copper sulfide, etc., organic electrically conductive materials, e.g., polyaniline, polythiophene, polypyrrole, etc., laminates of these materials with ITO, etc. Of these materials, electrically conductive metallic oxides are preferred, and ITO is especially preferred in view of productivity, high conductivity, transparency and the like.

The anode can be formed on the substrate in accordance with various methods arbitrarily selected from, for example, wet methods, e.g., a printing method, a coating method, etc., physical methods, e.g., a vacuum deposition method, a sputtering method, an ion plating method, etc., and chemical methods, e.g., a CVD method, a plasma CVD method, etc., taking the suitability with the material to be used in the anode into consideration. For example, in the case of selecting ITO as the material of the anode, the anode can be formed according to a direct current or high frequency sputtering method, a vacuum deposition method, an ion plating method, etc.

In the organic electroluminescent device in the invention, the position of the anode to be formed is not especially restricted and can be formed anywhere in accordance with the intended use and purpose of the luminescent device, but preferably provided on the substrate. In this case, the anode may be formed on the entire surface of one side of the substrate, or may be formed at a part.

As patterning in forming the anode, patterning may be performed by chemical etching such as by photo-lithography, may be carried out by physical etching by laser and the like, may be performed by vacuum deposition or sputtering on a superposed mask, or a lift-off method and a printing method may be used.

The thickness of the anode can be optionally selected in accordance with the materials of the anode, so that it cannot be regulated unconditionally, but the thickness is generally from 10 nm to 50 μm or so, and is preferably from 50 nm to 20 μm.

The value of resistance of the anode is preferably 10³Ω/□ or less, and more preferably 10²Ω/□ or less. In the case where the anode is transparent, it may be colorless and transparent, or may be colored and transparent. For collecting emission from the transparent anode side, the transmittance is preferably 60% or more, and more preferably 70% or more.

In connection with transparent anodes, description is found in Yutaka Sawada supervised, Tomei Denkyoku-Maku no Shintenkai (New Development in Transparent Conductive Films), CMC Publishing Co., Ltd. (1999), and the description therein can be applied to the invention. In the case of using a plastic substrate low in heat resistance, a transparent anode film formed with ITO or IZO at a low temperature of 150° C. or less is preferred.

Cathode:

The cathode is generally sufficient to have the function of the electrode to inject electrons to organic layers. The shape, structure and size of the cathode are not especially restricted, and these can be arbitrarily selected from known materials of electrode in accordance with the intended use and purpose of the luminescent device.

As the materials to constitute the cathode, for example, metals, alloys, metallic oxides, electrically conductive compounds, and mixtures of these materials are exemplified. The specific examples of the materials of cathode include alkali metals (e.g., Li, Na, K, Cs, etc.), alkaline earth metals (e.g., Mg, Ca, etc.), gold, silver, lead, aluminum, sodium-potassium alloy, lithium-aluminum alloy, magnesium-silver alloy, indium, rare earth metals, e.g., ytterbium, etc. These materials may be used by one kind alone, but from the viewpoint of the compatibility of stability and an electron injecting property, two or more kinds of materials can be preferably used in combination.

As the materials constituting the cathode, alkali metals and alkaline earth metals are preferred of these materials in the point of an electron injecting property, and materials mainly comprising aluminum are preferred for their excellent preservation stability.

The materials mainly comprising aluminum mean aluminum alone, alloys of aluminum with 0.01 to 10 mass % of alkali metal or alkaline earth metal, or mixtures of these (e.g., lithium-aluminum alloy, magnesium-aluminum alloy, etc.).

The materials of the cathode are disclosed in detail in JP-A-2-15595 and IP-A-5-121172, and the materials described in these patents can also be used in the invention.

The cathode can be formed by known methods with no particular restriction. For example, the cathode can be formed according to wet methods, e.g., a printing method, a coating method, etc., physical methods, e.g., a vacuum deposition method, a sputtering method, an ion plating method, etc., and chemical methods, e.g., a CVD method, a plasma CVD method, etc., taking the suitability with the material constituting the cathode into consideration. For example, in the case of selecting metals as the materials of the cathode, the cathode can be formed with one or two or more kinds of the materials at the same time or in order by a sputtering method, etc.

Patterning in forming the cathode may be performed by chemical etching such as a method by photo-lithography, may be carried out by physical etching such as a method by laser, may be performed by vacuum deposition or sputtering on a superposed mask, or a lift-off method and a printing method may be used.

The position of the cathode to be formed is not especially restricted and can be formed anywhere in the invention. The cathode may be formed on the entire surface of the organic layer, or may be formed at a part.

A dielectric layer comprising fluoride or oxide of alkali metal or alkaline earth metal may be inserted between the cathode and the organic layer in a thickness of from 0.1 to 5 nm. The dielectric layer can be regarded as a kind of an electron-injecting layer. The dielectric layer can be formed, for example, according to a vacuum deposition method, a sputtering method, an ion plating method, etc.

The thickness of the cathode can be optionally selected in accordance with the materials of the cathode, so that it cannot be regulated unconditionally, but the thickness is generally from 10 nm to 5 μm or so, and is preferably from 50 nm to 1 μm.

The cathode may be transparent or opaque. The transparent cathode can be formed by forming a film of the material of the cathode in a thickness of from 1 to 10 nm, and further laminating transparent conductive materials such as ITO and Organic Layers:

Organic layers in the invention will be described below.

The organic electroluminescence device in the invention has at least one organic layer including a light-emitting layer between a pair of electrodes, and as the organic layers other than the light-emitting layer, a hole transporting layer, an electron transporting layer, a charge blocking layer, a hole injecting layer, and an electron injecting layer are exemplified, as described above.

Forming Method of Organic Layers:

In the organic electroluminescence device of the invention, each layer constituting the organic layers can be suitably formed by any of dry film-forming methods such as a vacuum deposition method, a sputtering method, etc., a transfer method, and a printing method, etc.

Organic Light-Emitting Layer:

The light-emitting layer is a layer having functions to receive, at the time of electric field application, holes from the anode, hole injecting layer or hole transporting layer, and to receive electrons from the cathode, electron injecting layer or electron transporting layer, and offer the field of recombination of holes and electrons to emit light. The light-emitting layer may be a single layer, or may comprise two or more layers, and each layer may emit light in different luminescent color.

The light-emitting layer in the invention may consist of light-emitting materials alone, or may comprise a mixed layer of a host material and a light-emitting material. As the host material, the compound represented by formula (I) of the invention is preferred, but compounds other than the compound according to the invention may be used in combination or alone. The details will be described in the item of “Host Materials” later. Further, a material not having a charge-transporting property and not emitting light may be contained in the light-emitting layer.

Light-Emitting Materials:

The light-emitting material may be a phosphorescent material or a fluorescent material, and one or two or more kinds may be used.

The light-emitting layer in the invention can contain two or more light-emitting materials for the purpose of improving color purity and widening light emission wavelength region.

The at least one light-emitting material may be a phosphorescent material.

Fluorescent Materials:

The examples of fluorescent materials that can be used in the invention include various metal complexes represented by metal complexes of benzoxazole derivatives, benzimidazole derivatives, benzothiazole derivatives, styrylbenzene derivatives, polyphenyl derivatives, diphenylbutadiene derivatives, tetraphenylbutadiene derivatives, naphthalimide derivatives, coumarin derivatives, condensed aromatic compounds, perinone derivatives, oxadiazole derivatives, oxazine derivatives, aldazine derivatives, pyraridine derivatives, cyclopentadiene derivatives, bisstyrylanthracene derivatives, quinacridone derivatives, pyrrolopyridine derivatives, thiadiazolopyridine derivatives, cyclopentadiene derivatives, styrylamine derivatives, diketopyrrolopyrrole derivatives, aromatic dimethylidyne compounds, 8-quinolinol derivatives, pyromethene derivatives, polymer compounds such as polythiophene, polyphenylene, polyphenylenevinylene, etc., and compounds such as organic silane derivatives.

Phosphorescent Materials:

As the examples of phosphorescent materials that can be used in the invention, complexes containing a transition metal atom or a lanthanoid atom are exemplified.

For example, the transition metal atoms are not especially restricted, but preferably ruthenium, rhodium, palladium, tungsten, rhenium, osmium, iridium, and platinum are exemplified, more preferably rhenium, iridium and platinum, and still more preferably iridium and platinum are exemplified.

As the lanthanoid atoms, e.g., lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium are exemplified, and neodymium, europium and gadolinium are preferred of these lanthanoid atoms.

As the examples of ligands of complexes, the ligands described, for example, in G. Wilkinson et al., Comprehensive Coordination Chemistry, Pergamon Press (1987), H. Yersin, Photochemistry and Photophysics of Coordination Compounds, Springer-Verlag (1987), and Akio Yamamoto, Yuki Kinzoku Kagu-Kiso to Oyo-(Organic Metal Chemistry—Elements and Applications), Shokabo Publishing Co. (1982) are exemplified.

As the specific examples of ligands, halogen ligands (preferably a chlorine ligand), aromatic carbocyclic ligands (preferably having from 5 to 30 carbon atoms, more preferably from 6 to 30 carbon atoms, still more preferably from 6 to 20 carbon atoms, and especially preferably from 6 to 12 carbon atoms, e.g., a cyclopentadienyl anion, a benzene anion, a naphthyl anion, etc.), nitrogen-containing heterocyclic ligands (preferably having from 5 to 30 carbon atoms, more preferably from 6 to 30 carbon atoms, still more preferably from 6 to 20 carbon atoms, and especially preferably from 6 to 12 carbon atoms, e.g., pyrazolylpyridine, pyrrolylpyridine, imidazolylpyridine, triazolylpyridine, phenylisoquinoline, picolinic acid, phenylpyridine, benzoquinoline, quinolinol, bipyridyl, phenanthroline, etc.), diketone ligands (e.g., acetylacetone, etc.), carboxylic acid ligands (preferably having from 2 to 30 carbon atoms, more preferably from 2 to 20 carbon atoms, and still more preferably from 2 to 16 carbon atoms, e.g., an acetic acid ligand, etc.), alcoholate ligands (preferably having from 1 to 30 carbon atoms, more preferably from 1 to 20 carbon atoms, and still more preferably from 6 to 20 carbon atoms, e.g., a phenolate ligand, etc.), silyloxy ligands (preferably having from 3 to 40 carbon atoms, more preferably from 3 to 30 carbon atoms, and still more preferably from 3 to 20 carbon atoms, e.g., a trimethylsilyloxy ligand, a dimethyl-tert-butysilyloxy ligand, a triphenylsilyloxy ligand, etc.), carbon monoxide ligands, isonitrile ligands, cyano ligands, phosphorus ligands (preferably having from 3 to 40 carbon atoms, more preferably from 3 to 30 carbon atoms, still more preferably from 3 to 20 carbon atoms, and especially preferably from 6 to 20 carbon atoms, e.g., a triphenylphosphine ligand, etc.), thiolate ligands (preferably from 1 to 30 carbon atoms, more preferably from 1 to 20 carbon atoms, and still more preferably from 6 to 20 carbon atoms, e.g., a phenylthiolate ligand, etc.), phosphine oxide ligands (preferably having from 3 to 30 carbon atoms, more preferably from 8 to 30 carbon atoms, and still more preferably from 18 to 30 carbon atoms, e.g., a triphenylphosphine oxide ligand, etc.) are preferably exemplified, and more preferably nitrogen-containing heterocyclic ligands are exemplified.

These complexes may have one transition metal atom in a compound, or they may be what are called polynuclear complexes having two or more transition metal atoms. They may contain dissimilar metal atoms at the same time.

As the phosphorescent materials, iridium complexes and platinum complexes are preferred, in particular, platinum complexes having a tetradentate ligand and platinum complexes having fluorine-substituted phenylpyridine as the ligand are preferred, and platinum complexes having a tetradentate ligand are most preferred.

The specific examples of the phosphorescent materials include phosphorescent compounds disclosed, for example, in U.S. Pat. Nos. 6,303,238B1, 6,097,147, 6,653,654, WO 00/57,676, WO 00/70,655, WO 01/08,230, WO 01/39,234A2, WO 01/41,512A1, WO 02/02,714A2, WO 02/15,645A1, WO 02/44,189A1, WO 04/108,857, WO 04/081,017, WO 04/085,450, WO 05/113,704, WO 05/019,373A2, WO 05/042,444, WO 05/042,550, WO 06/098,505, WO 06/121,811, WO 06/014,599, WO 07/095,118, JP-A-2001-247859, JP-A-2002-302671, JP-A-2002-117978, JP-A-2003-133074, JP-A-2002-235076, JP-A-2003-123982, JP-A-2002-170684, EP 1,211,257, JP-A-2002-226495, JP-A-2002-234894, JP-A-2001-247859, JP-A-2001-298470, JP-A-2002-173674, JP-A-2002-203678, JP-A-2002-203679, JP-A-2004-357791, JP-A-2005-310733, JP-A-2005-317516, JP-A-2006-261623, JP-A-2006-232784, JP-A-2006-256999, JP-A-2007-19462, JP-A-2007-84635, and JP-A-2007-96259. Further, as other complex phosphorescent materials, compounds described in Coordination Chemistry Reviews, 250, pp. 2093-2126 (2006) are exemplified.

As phosphorescent materials, iridium complexes, platinum complexes and rhenium complexes having at least one coordination manner of a metal-carbon bond, a metal-nitrogen bond, a metal-oxygen bond, and a metal-sulfur bond are preferred. Further, from the viewpoints of luminous efficiency, driving durability and chromaticity, an iridium complex, a platinum complex and a rhenium complex containing a tridentate or higher multidentate ligand are especially preferred. A platinum complex having a tridentate or tetradentate ligand is most preferred.

As the platinum complex, a platinum complex represented by the following formula (C-1) is preferred.

In formula (C-1), each of Q¹, Q², Q³ and Q⁴ independently represents a ligand to coordinate to Pt; and each of L¹, L² and L³ independently represents a single bond or a divalent liking group.

The platinum complex represented by formula (C-1) will be explained below. Each of Q¹, Q², Q³ and Q⁴ independently represents a ligand to coordinate to Pt. At this time, bonding of Q¹, Q², Q¹ and Q⁴ to Pt may be any of a covalent bond, an ionic bond, and a coordinate bond. The atoms in Q¹, Q², Q³ and Q⁴ to bond to Pt are preferably a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom and a phosphorus atom, and it is preferred that at least one of the atoms in Q¹, Q², Q³ and Q⁴ to bond to Pt is a carbon atom, and it is more preferred that two of these atoms are carbon atoms.

Q¹, Q², Q³ and Q⁴ to bond to Pt via a carbon atom may be an anionic ligand or a neutral ligand. As the anionic ligands, a vinyl ligand, an aromatic hydrocarbon ring ligand (e.g., a benzene ligand, a naphthalene ligand, an anthracene ligand, a phenanthrene ligand, etc.), a heterocyclic ligand (e.g., a furan ligand, a thiophene ligand, a pyridine ligand, a pyrazine ligand, a pyrimidine ligand, a pyridazine ligand, a triazine ligand, a thiazole ligand, an oxazole ligand, a pyrrole ligand, an imidazole ligand, a pyrazole ligand, a triazole ligand, and condensed ring products containing these ligands (e.g., a quinoline ligand, a benzothiazole ligand, etc.)) are exemplified. As the neutral ligand, a carbene ligand is exemplified.

Q¹, Q², Q³ and Q⁴ to bond to Pt via a nitrogen atom may be a neutral ligand or an anionic ligand. As the neutral ligands, a nitrogen-containing aromatic heterocyclic ligand (a pyridine ligand, a pyrazine ligand, a pyrimidine ligand, a pyridazine ligand, a triazine ligand, an imidazole ligand, a pyrazole ligand, a triazole ligand, an oxazole ligand, a thiazole ligand, and condensed ring products containing these ligands (e.g., a quinoline ligand, a benzimidazole ligand, etc.)), an amine ligand, a nitrile ligand, and an imine ligand are exemplified. As the anionic ligands, an amino ligand, an imino ligand, a nitrogen-containing aromatic heterocyclic ligand (e.g., a pyrrole ligand, an imidazole ligand, a triazole ligand, and condensed ring products containing these ligands (e.g., an indole ligand, a benzimidazole ligand, etc.)) are exemplified.

Q¹, Q², Q³ and Q⁴ to bond to Pt via an oxygen atom may be a neutral ligand or an anionic ligand. As the neutral ligands, an ether ligand, a ketone ligand, an ester ligand, an amido ligand, an oxygen-containing heterocyclic ligand (e.g., a furan ligand, an oxazole ligand, and condensed ring products containing these ligands (e.g., a benzoxazole ligand, etc.)) are exemplified. As the anionic ligands, an alkoxy ligand, an aryloxy ligand, a hetero-aryloxy ligand, an acyloxy ligand, a silyloxy ligand, etc., are exemplified.

Q¹, Q², Q³ and Q⁴ to bond to Pt via a sulfur atom may be a neutral ligand or an anionic ligand. As the neutral ligands, a thioether ligand, a thioketone ligand, a thioester ligand, a thioamide ligand, a sulfur-containing heterocyclic ligand (e.g., a thiophene ligand, a thiazole ligand, and condensed ring products containing these ligands (e.g., a benzothiazole ligand, etc.)) are exemplified. As the anionic ligands, an alkylmercapto ligand, an arylmercapto ligand, a hetero-arylmercapto ligand, etc., are exemplified.

Q¹, Q², Q³ and Q⁴ to bond to Pt via a phosphorus atom may be a neutral ligand or an anionic ligand. As the neutral ligands, a phosphine ligand, a phosphoric ester ligand, a phosphorous ester ligand, a phosphorus-containing ligand (e.g., a phosphinine ligand, etc.) are exemplified. As the anionic ligands, a phosphino ligand, a phosphinyl ligand, a phosphoryl ligand are exemplified.

Each of the groups represented by Q¹, Q², Q³ and Q⁴ may have a substituent, and as the substituents, those exemplified above as substituent group A can be arbitrarily applied. In addition, substituents may be linked to each other (when Q³ and Q⁴ are linked, the Pt complex is a Pt complex of a cyclic tetradentate ligand).

The groups represented by Q¹, Q², Q³ and Q⁴ are preferably an aromatic hydrocarbon ring ligand to bond to Pt via a carbon atom, an aromatic heterocyclic ligand to bond to Pt via a carbon atom, a nitrogen-containing aromatic heterocyclic ligand to bond to Pt via a nitrogen atom, an acyloxy ligand, an alkyloxy ligand, an aryloxy ligand, a hetero-aryloxy ligand, and a silyloxy ligand, more preferably an aromatic hydrocarbon ring ligand to bond to Pt via a carbon atom, an aromatic heterocyclic ligand to bond to Pt via a carbon atom, a nitrogen-containing aromatic heterocyclic ligand to bond to Pt via a nitrogen atom, an acyloxy ligand, and an aryloxy ligand, and still more preferably an aromatic hydrocarbon ring ligand to bond to Pt via a carbon atom, an aromatic heterocyclic ligand to bond to Pt via a carbon atom, a nitrogen-containing aromatic heterocyclic ligand to bond to Pt via a nitrogen atom, and an acyloxy ligand.

Each of L¹, L² and L³ represents a single bond or a divalent linking group. As the divalent linking groups represented by L¹, L² and L³, an alkylene group (e.g., methylene, ethylene, propylene, etc.), an arylene group (e.g., phenylene, naphthalenediyl), a hetero-arylene group (e.g., pyridinediyl, thiophenediyl, etc.), an imino group (—NR—) (e.g., a phenylimino group, etc.), an oxy group (—O—), a thio group (—S—), a phosphinidene group (—PR—) (e.g., a phenylphosphinidene group, etc.), a silylene group (—SiRR′—) (e.g., a dimethylsilylene group, a diphenylsilylene group, etc.), and groups obtained by combining these groups are exemplified. These linking groups may further have a substituent.

Each of L¹, L² and L³ preferably represents a single bond, an alkylene group, an arylene group, a hetero-arylene group, an imino group, an oxy group, a thio group, or a silylene group, more preferably a single bond, an alkylene group, an arylene group, or an imino group, still more preferably a single bond, an alkylene group, or an arylene group, still further preferably a single bond, a methylene group, or a phenylene group, still yet more preferably a single bond, a di-substituted methylene group, still yet further preferably a single bond, a dimethylmethylene group, a diethylmethylene group, a diisobutylmethylene group, a dibenzylmethylene group, an ethylmethylene group, a methylpropylmethylene group, an isobutylmethylmethylene group, a diphenylmethylene group, a methylphenylmethylene group, a cyclohexanediyl group, a cyclopentanediyl group, a fluorenediyl group, or a fluoromethylmethylene group, and especially preferably represents a single bond, a dimethylmethylene groups a diphenylmethylene group, or a cyclohexanediyl group.

The platinum complex represented by formula (C-1) is more preferably represented by the following formula (C-2).

In formula (C-2), L¹ represents a single bond or a divalent linking group; each of A¹, A², A³, A⁴, A⁵ and A⁶ independently represents C—R or N; R represents a hydrogen atom or a substituent; each of X¹ and X² represents C or N; and each of Z¹ and Z² represents a 5- or 6-membered aromatic ring or an aromatic heterocyclic ring formed together with X—C in the formula,

Formula (C-2) will be described below. L¹ has the same definition as in formula (C-1) and the preferred range is also the same. Each of A¹, A², A³, A⁴, A⁵ and A⁶ independently represents C—R or N. R represents a hydrogen atom or a substituent. As the substituents represented by R, those exemplified above as substituent group A can be applied.

Each of A¹, A², A³, A⁴, A⁵ and A⁶ preferably represents C—R, and R may be linked to each other to form a ring. When each of A¹, A², A³, A⁴, A⁵ and A⁶ represents C—R, R represented by A² and A⁵ is preferably a hydrogen atom, an alkyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, a fluorine group, or a cyano group, more preferably a hydrogen atom, an amino group, an alkoxy group, an aryloxy group, or a fluorine group, and especially preferably a hydrogen atom or a fluorine group. R represented by A¹, A³, A⁴ and A⁶ is preferably a hydrogen atom, an alkyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, a fluorine group, or a cyano group, more preferably a hydrogen atom, an amino group, an alkoxy group, an aryloxy group, or a fluorine group, and especially preferably a hydrogen atom. Each of X¹ and X² represents C or N. Z¹ represents a 5- or 6-membered aromatic hydrocarbon ring or an aromatic heterocyclic ring formed together with X¹—C in the formula. Z² represents a 5- or 6-membered aromatic hydrocarbon ring or an aromatic heterocyclic ring formed together with X²—C in the formula. As the aromatic hydrocarbon rings or the aromatic heterocyclic rings represented by Z¹ and Z², a benzene ring, a naphthalene ring, an anthracene ring, a pyrene ring, a phenanthrene ring, a perylene ring, a pyridine ring, a quinoline ring, an isoquinoline ring, a phenanthridine ring, a pyrimidine ring, a pyrazine ring, a pyridazine ring, a triazine ring, a cinnoline ring, an acridine ring, a phthalazine ring, a quinazoline ring, a quinoxaline ring, a naphthyridine ring, a pteridine ring, a pyrrole ring, a pyrazole ring, a triazole ring, an indole ring, a carbazole ring, an indazole ring, a benzimidazole ring, an oxazole ring, a thiazole ring, an oxadiazole ring, a thiadiazole ring, a benzoxazole ring, a benzothiazole ring, an imidazopyridine ring, a thiophene ring, a benzothiophene ring, a furan ring, a benzofuran ring, a phosphor ring, a phosphinine ring, and a silol ring are exemplified. Z¹ and Z² may have a substituent, and as the substituents, those exemplified above as substituent group A can be applied. Further, Z¹ and Z² may form a condensed ring with other rings.

Each of Z¹ and Z² preferably represents a benzene ring, a naphthalene ring, a pyrazole ring, an imidazole ring, a triazole ring, a pyridine ring, an indole ring or a thiophene ring, and more preferably a benzene ring, a pyrazole ring or a pyridine ring.

The platinum complex represented by formula (C-2) is more preferably represented by the following formula (C-3),

In formula (C-3), each of A¹ to A¹³ independently represents C—R or N. R represents a hydrogen atom or a substituent. L¹ represents a single bond or a divalent linking group.

As the specific examples of the light-emitting materials, for example, the following are exemplified, but the invention is not restricted thereto.

The light-emitting material is generally contained in the light-emitting layer in an amount of from 0.1 to 50 mass % based on the mass of all the compounds forming the light-emitting layer, preferably from 0.2 to 50 mass % in view of durability and external quantum efficiency, and more preferably from 0.5 to 40 mass %.

The phosphorescent material is preferably contained in the light-emitting layer in an amount of from 0.1 to 40 mass %, and more preferably from 0.5 to 20 mass %.

The thickness of the light-emitting layer is not especially restricted, but generally preferably the thickness is from 1 to 500 nm, more preferably from 5 to 200 nm, and still more preferably from 10 to 100 nm.

Host Materials:

As host materials contained in the light-emitting layer in the invention, besides the compounds of the invention, for example, compounds having a carbazole structure, compounds having a diarylamine structure, compounds having a pyridine structure, compounds having a pyrazine structure, compounds having a triazine structure, and compounds having an arylsilane structure, and materials exemplified in the items of the later-described hole injecting layer, hole transporting layer, electron injecting layer, and electron transporting layer are exemplified.

The host materials are preferably charge-transporting materials. The host material may be used by one kind alone or two or more kinds may be used, and, for example, the constitution of the mixture of an electron transporting host material and a hole transporting host material is exemplified.

The content of the host compound in the invention is not especially restricted, but from the aspects of luminous efficiency and driving voltage, the content of the host compound is preferably 5 mass % or more and 99.5 mass % or less based on the mass of all the compounds forming the light-emitting layer, and more preferably 15 mass % or more and 95 mass % or less.

Hole Injecting Layer and Hole Transporting Layer:

The hole injecting layer and the hole transporting layer are layers having the functions of receiving holes from the anode or anode side and transporting the holes to the cathode side. The hole injecting layer and the hole transporting layer are preferably layers specifically containing, besides the compounds according to the invention, carbazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidyne compounds, porphyrin compounds, organic silane derivatives, or carbon.

The hole injecting layer or hole transporting layer of the organic EL device in the invention can contain an electron accepting dopant. As the electron accepting dopants to be introduced to the hole injecting layer or hole transporting layer, either inorganic compounds or organic compounds can be used so long as they are electron-acceptive and have a property capable of oxidizing organic compounds.

Specifically, the examples of the inorganic compounds include metal halides, such as ferric chloride, aluminum chloride, gallium chloride, indium chloride, and antimony pentachloride, and metallic oxides, such as vanadium pentoxide and molybdenum trioxide.

In the case of organic compounds, compounds having a nitro group, halogen, a cyano group or a trifluoromethyl group as the substituent, quinone compounds, acid anhydride compounds and Fullerene can be preferably used.

In addition to the above compounds, the compounds disclosed in JP-A-6-212153, JP-A-11-111463, JP-A-11-251067, JP-A-2000-196140, JP-A-2000-286054, JP-A-2000-315580, JP-A-2001-102175, JP-A-2001-160493, JP-A-2002-252085, JP-A-2002-56985, JP-A-2003-157981, JP-A-2003-217862, JP-A-2003-229278, JP-A-2004-342614, JP-A-2005-72012, JP-A-2005-166637 and JP-A-2005-209643 can be preferably used.

Of the compounds, hexacyanobutadiene, hexacyanobenzene, tetracyanoethylene, tetracyanoquinodimethane, tetrafluorotetracyanoquinodimethane, p-fluoranyl, p-chloranyl, p-bromanyl, p-benzoquinone, 2,6-dichlorobenzoquinone, 2,5-dichlorobenzoquinone, 1,2,4,5-tetracyanobenzene, 1,4-dicyanotetrafluorobenzene, 2,3-dichloro-5,6-dicyanobenzoquinone, p-dinitrobenzene, m-dinitrobenzene, o-dinitrobenzene, 1,4-naphthoquinone, 2,3-dichloronaphthoquinone, 1,3-dinitronaphthalene, 1,5-dinitronaphthalene, 9,10-anthraquinone, 1,3,6,8-tetranitrocarbazole, 2,4,7-trinitro-9-fluorenone, 2,3,5,6-tetracyanopyridine, and Fullerene C60 are preferred, hexacyanobutadiene, hexacyanobenzene, tetracyanoethylene, tetracyanoquinodimethane, tetrafluorotetracyanoquinodimethane, p-fluoranyl, p-chloranyl, p-bromanyl, 2,6-dichlorobenzoquinone, 2,5-dichlorobenzoquinone, 2,3-dichloronaphthoquinone, 1,2,4,5-tetracyanobenzene, 2,3-dichloro-5,6-dicyanobenzoquinone, and 2,3,5,6-tetracyanopyridine are more preferred, and tetrafluorotetracyanoquinodimethane is especially preferred.

These electron accepting dopants may be used by one kind alone, or two or more dopants may be used. The amount to be used of the electron accepting dopants differs according to the kind of the material, but the amount is preferably from 0.01 to 50 mass % on the basis of the material of the hole transporting layer, more preferably from 0.05 to 20 mass %, and especially preferably from 0.1 to 10 mass %.

The thickness of the hole-injecting layer and hole transporting layer is each preferably 500 nm or less in view of lowering driving voltage.

The thickness of the hole-transporting layer is preferably from 1 to 500 nm, more preferably from 5 to 200 nm, and still more preferably from 10 to 100 nm. The thickness of the hole-injecting layer is preferably from 0.1 to 200 nm, more preferably from 0.5 to 100 nm, and still more preferably from 1 to 100 nm.

The hole-injecting layer and the hole-transporting layer may have a single layer structure comprising one kind or two or more kinds of the above materials, or may be a multilayer structure comprising a plurality of layers having the same composition or different compositions.

Electron Injecting Layer and Electron Transporting Layer:

The electron-injecting layer and the electron-transporting layer are layers having functions of receiving electrons from the cathode or cathode side and transporting the electrons to the anode side. The electron-injecting layer and the electron-transporting layer are preferably layers specifically containing, besides the compounds according to the invention, various metal complexes represented by metal complexes of triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, fluorenone derivatives, anthraquinodimethane derivatives, anthrone derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimide derivatives, fluorenylidenemethane derivatives, distyrylpyrazine derivatives, aromatic cyclic tetracarboxylic anhydrides such as naphthalene and perylene, phthalocyanine derivatives, S-quinolinol derivatives, metal complexes having metalphthalocyanine, benzoxazole or benzothiazole as the ligand, or organic silane derivatives.

The electron-injecting layer and the electron-transporting layer of the organic EL device of the invention can contain an electron donating dopant. The electron donating dopants to be introduced to the electron-injecting layer and the electron-transporting layer are sufficient to be electron donating and have a property capable of reducing organic compounds, and alkali metals such as Li, alkaline earth metals such as Mg, transition metals containing rare earth metals, and reductive organic compounds are preferably used. As the metals, metals having a work function of 4.2 eV or less can be preferably used, and specifically Li, Na, K, Be, Mg, Ca, Sr, Ba, Y, Cs, La, Sm, Gd, and Yb are exemplified. As the reductive organic compounds, e.g., nitrogen-containing compounds, sulfur-containing compounds and phosphorus-containing compounds are exemplified.

In addition to the above, materials disclosed in JP-A-6-212153, JP-A-2000-196140, JP-A-2003-68468, JP-A-2003-229278 and JP-A-2004-342614 can be used.

These electron-donating dopants may be used by one kind alone, or two or more kinds of dopants may be used. The amount to be used of the electron-donating dopants differs by the kinds of materials, but the amount is preferably from 0.1 to 99 mass % on the basis of the electron transporting layer material, more preferably from 1.0 to 80 mass %, and especially preferably from 2.0 to 70 mass %.

The thickness of the electron injecting layer and the electron transporting layer is preferably 500 nm or less from the point of lowering the driving voltage.

The thickness of the electron transporting layer is preferably from 1 to 500 nm, more preferably from 5 to 200 nm, and still more preferably from 10 to 100 nm. The thickness of the electron injecting layer is preferably from 0.1 to 200 nm, more preferably from 0.2 to 100 nm, and still more preferably from 0.5 to 50 nm.

The electron injecting layer and the electron transporting layer may have a single layer structure comprising one kind or two or more kinds of the above materials, or may be a multilayer structure comprising a plurality of layers having the same composition or different compositions.

Hole-Blocking Layer:

The hole-blocking layer is a layer having a function of preventing the holes transported from the anode side to the light-emitting layer from passing through to the cathode side. In the invention, a hole-blocking layer can be provided as an organic layer contiguous to the light-emitting layer on the cathode side.

As the examples of the compounds constituting the hole-blocking layer, aluminum complexes such as aluminum(III) bis(2-methyl-5-quinolinato)-4-phenylphenolate (abbreviation: BAlq), triazole derivatives, and phenanthroline derivatives such as 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (abbreviation: BCP) can be exemplified.

The thickness of the hole-blocking layer is preferably from 1 to 500 nm, more preferably from 5 to 200 nm, and still more preferably from 10 to 100 nm.

The hole-blocking layer may have a single layer structure comprising one kind or two or more kinds of the above materials, or may be a multilayer structure comprising a plurality of layers having the same composition or different compositions.

Electron-Blocking Layer:

The electron-blocking layer is a layer having a function of preventing the electrons transported from the cathode side to the light-emitting layer from passing through to the anode side. In the invention, an electron-blocking layer can be provided as an organic layer contiguous to the light-emitting layer on the anode side.

As the examples of the compounds constituting the electron-blocking layer, for example, the hole-transporting materials described above can be applied.

The thickness of the electron-blocking layer is preferably from 1 to 500 nm, more preferably from 5 to 200 nm, and still more preferably from 10 to 100 nm.

The electron-blocking layer may have a single layer structure comprising one kind or two or more kinds of the above materials, or may be a multilayer structure comprising a plurality of layers having the same composition or different compositions.

Protective Layer:

In the invention, the organic EL device may be entirely protected with a protective layer.

The materials contained in the protective layer are sufficient to have a function of preventing substances that accelerate deterioration of the device such as water and oxygen from entering the device.

As the examples of the materials, metals, e.g., In, Sn, Pb, Au, Cu, Ag, Al, Ti, Ni, etc., metallic oxides, e.g., MgO, SiO, SiO₂, Al₂O₃, GeO, NiO, CaO, BaO, Fe₂CO₃, Y₂O₃, TiO₂, etc., metallic nitrides, e.g., SiN_(x), SiN_(x)O_(y), etc., metallic fluorides, e.g., MgF₂, LiF, AlF₃, CaF₂, etc., copolymers of any of polyethylene, polypropylene, polymethyl methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, and chlorotrifluoroethylene with dichlorodifluoroethylene, copolymers obtained by copolymerization of tetrafluoroethylene and monomer mixture containing at least one kind of comonomer, fluorine-containing copolymers having a cyclic structure in the copolymer main chain, water-absorbing materials having a coefficient of water absorption of 1% or more, and moisture-proof materials having a coefficient of water absorption of 0.1% or less are exemplified.

The method of forming the protective layer is not especially restricted and, for example, a vacuum deposition method, a sputtering method, a reactive sputtering method, an MBE (molecular beam epitaxy) method, a cluster ion beam method, an ion plating method, a plasma polymerization method (a high frequency excitation ion plating method), a plasma CVD method, a laser CVD method, a thermal CVD method, a gas source CVD method, a coating method, a printing method, and a transfer method can be used.

Sealing Case:

The organic electroluminescence device in the invention may be entirely scaled with a sealing case.

A water-absorbing agent or an inactive liquid may be sealed in the space between the sealing case and the luminescence device. The water-absorbing agent is not especially restricted, and, for example, barium oxide, sodium oxide, potassium oxide, calcium oxide, sodium sulfate, calcium sulfate, magnesium sulfate, phosphorus pentoxide, calcium chloride, magnesium chloride, copper chloride, cesium fluoride, niobium fluoride, calcium bromide, vanadium bromide, molecular sieve, zeolite, and magnesium oxide can be exemplified. The inactive liquid is not especially restricted, and, for example, paraffins, liquid paraffins, fluorine solvents, e.g., perfluoroalkane, perfluoroamine, perfluoroether, etc., chlorine solvents, and silicone oils can be exemplified

A method of sealing with the following shown resin sealing layer is also preferably used.

Resin Sealing Layer:

It is preferred to restrain deterioration of performance of the functional device of the invention due to oxygen and moisture by bringing into contact with air by the resin sealing layer.

Materials:

The materials of the resin sealing layer are not especially restricted, and acrylic resins, epoxy resins, fluorine resins, silicon resins, rubber resins, and ester resins can be used, and epoxy resins are preferred in the point of moisture content-preventing function. Of epoxy resins, thermosetting epoxy resins and photo-curable epoxy resins are preferred.

Manufacturing Method:

The manufacturing method of the resin sealing layer is not especially restricted and, for example, a method of coating a resin solution, a method of contact bonding or thermal contact bonding of a resin sheet, and a method of dry polymerization by deposition or sputtering are exemplified.

Film Thickness:

The thickness of the resin sealing layer is preferably 1 μm or more and 1 mm or less, more preferably 5 μm or more and 100 μm or less, and most preferably 10 μm or more and 50 μm or less. When the resin sealing layer is thinner than the above range, there is a possibility that the inorganic film is damaged when a second substrate is applied. While when the resin sealing layer is thicker than the above range, the thickness of the organic electroluminescence device itself becomes thick and a thin film property of the characteristics of the organic electroluminescence device is impaired.

Sealing Adhesive:

Sealing adhesive for use in the invention has a function of preventing water and oxygen from getting in from the edge parts.

Materials:

As the materials of the sealing adhesives, the same materials as the materials used in the resin sealing layer can be used. From the point of waterproofing, epoxy resins are preferred and photo-curable adhesives and thermosetting adhesives are preferred above all.

It is also preferred to add fillers to the above materials.

As the fillers to be added to the sealing agent, inorganic materials such as SiO₂, SiO (silicon oxide), SiON (silicon oxide nitride) and SiN (silicon nitride) are preferred. By the addition of fillers, the viscosity of the sealing agent increases, processing suitability is bettered, and a moisture-proofing property is improved.

Desiccant:

The sealing adhesive may contain a desiccant. As the desiccant, barium oxide, calcium oxide, and strontium oxide are preferably used.

The addition amount of the desiccant to the sealing adhesive is preferably from 0.01 to 20 mass %, and more preferably from 0.05 to 15 mass %. When the addition amount is less than the above range, the effect of the addition of the desiccant decreases, while when the amount is greater than the above range, it is difficult to uniformly disperse the desiccant in the sealing adhesive, so that not preferred.

Prescription of Sealing Adhesive:

Polymer Composition, Concentration

The sealing adhesive is not especially restricted and the above materials can be used. For example, as the photo-curable epoxy adhesive, XNR5516 (manufactured by Nagase Chemtex Corporation) can be exemplified, and it is sufficient that the desiccant is directly added thereto and dispersed.

Thickness

The coating thickness of the sealing adhesive is preferably from 1 μm to 1 mm. When the coating thickness is thinner than that, the sealing adhesive cannot be coated uniformly and not preferred. When the thickness is greater than that, a way for water to enter widens, so that not preferred.

Method of Sealing:

In the invention, a functional device can be obtained by coating the sealing adhesive containing the desiccant by means of a dispenser and the like, and superposing a second substrate thereon after coating and hardening.

Driving:

By the application of D.C. (if necessary, A.C. component may be contained) voltage (generally from 2 to 15 volts) between the anode and the cathode, or by the application of D.C. electric current, light emission of the organic electroluminescence device of the invention can be obtained.

With respect to the driving method of the organic electroluminescence device of the invention, the driving methods disclosed in JP-A-2-148687, JP-A-6-301355, JP-A-5-29080, JP-A-7-134558, JP-A-8-234685, JP-A-8-241047, Japanese Patent 2784615, U.S. Pat. Nos. 5,828,429 and 6,023,308 can be applied to the invention.

The luminescence device of the invention can be improved in the efficiency of collection of light by various known contrivances. For example, it is possible to improve efficiency of collection of light and improve external quantum efficiency by processing the shape of the substrate surface (for example, by forming a minute rugged pattern), by controlling the refractive indices of the substrate, ITO layer and organic layers, and by controlling the thicknesses of the substrate, ITO layer and organic layers.

The luminescence device of the invention may be what is called top emission system of collecting light from the anode side.

The organic EL device of the invention can take a structure of providing a charge-generating layer between each two layers of a plurality of light-emitting layers for improving luminous efficiency.

The charge-generating layer has functions of generating charge (holes and electrons) at the time of application of electric field and injecting the generated charge to the layer contiguous to the charge-generating layer.

As the material for forming the charge-generating layer, any material can be used so long as it has the above functions, and the charge-generating layer may comprise a single compound or a plurality of compounds.

Specifically, the material may be a material having conductivity, may be a material having semi-conductivity such as a doped organic layer, or may be a material having an electric insulating property, and the materials disclosed in JP-A-11-329748, JP-A-2003-272860 and JP-A-2004-39617 can be exemplified.

More specifically, transparent conductive materials such as ITO and IZO (indium zinc oxide), Fullerenes such as C60, conductive organic materials such as oligothiophene, conductive organic materials such as metallic phthalocyanines, metal-free phthalocyanines, metallic porphyrins, and metal-free porphyrins, metallic materials such as Ca, Ag, Al, Mg—Ag alloy, Al—Li alloy, and Mg—Li alloy, hole-conductive materials, electron-conductive materials, and mixtures of these materials may be used.

As the hole-conductive materials, for example, materials obtained by doping oxidants having an electron-withdrawing property such as F4-TCNQ, TCNQ, FeCl₃ to hole-transporting organic materials such as 2-TNATA and NPD, P-type conductive polymers, and P-type semiconductors are exemplified. As the electron-conductive materials, for example, materials obtained by doping metals or metallic compounds having a work function of less than 4.0 eV to electron-transporting organic materials, N-type conductive polymers, and N-type semiconductors are exemplified. As the N-type semiconductors, N-type Si, N-type CdS, and N-type ZnS are exemplified, and the P-type semiconductors, P-type Si, P-type dTe, and P-type CuO are exemplified.

Further, an electrically insulating material such as V₂O₃ can also be used as the charge-generating layer.

The charge-generating layer may be a monolayer, or a laminate of a plurality of layers. As the structure of lamination of a plurality of layers, a layer having a structure of the lamination of a material having conductivity such as a transparent conductive material or a metallic material and a hole-conductive material or an electron-conductive material, and a layer having a structure of the lamination of the hole-conductive material and the electron-conductive material are exemplified.

The thickness is not especially restricted, but is preferably from 0.5 to 200 nm, more preferably from 1 to 100 nm, still more preferably from 3 to 50 nm, and especially preferably from 5 to 30 nm.

It is preferred to select the thickness and material of the charge-generating layer so that the transmittance of visible light is 50% or more. The forming method of the charge-generating layer is not especially restricted, and the forming method of the organic layers can be used.

The charge-generating layer is formed between each two layers of a plurality of light-emitting layers, and the anode side and the cathode side of the charge generating layer may contain materials having a function of injecting charge to the contiguous layers. For heightening an electron injecting property to the layer contiguous to the anode side, electron injecting compounds such as BaO, SrO, Li₂O, LiCl, LiF, MgF₂, MgO, CaF₂ may be laminated on the anode side of the charge-generating layer.

Besides the above description, the materials of the charge-generating layer can be selected with reference to JP-A-2003-45676, U.S. Pat. Nos. 6,337,492, 6,107,734 and 6,872,472.

The organic EL device in the invention may have a resonator structure. For example, the organic EL device has a multilayer film mirror comprising a plurality of laminated films different in refractive index, a transparent or translucent electrode, a light-emitting layer, and a metal electrode by superposition on a transparent substrate. The light generated from the light-emitting layer repeats reflection and resonates between the multilayer film mirror and the metal electrode as reflectors.

As another preferred embodiment, a transparent or translucent electrode and a metal electrode respectively function as reflectors on a transparent substrate, and light generated from the light-emitting layer repeats reflection and resonates between them.

To form a resonance structure, effective refractive indices of two reflectors, optical path determined by the refractive index and thickness of each layer between the reflectors are adjusted to be optimal values to obtain a desired resonance wavelength. The expression of the case of the first embodiment is disclosed in JP-A-9-180883. The expression of the case of the second embodiment is disclosed in JP-A-2004-127795.

Use of the Invention:

The organic electroluminescence device in the invention can be preferably used in display devices, displays, backlights, electrophotography, illumination light sources, recording light sources, exposure light sources, reading light sources, indicators, signboards, interior designs, optical communications, and the like.

As a method of making the organic EL device full colors, for example, as described in Monthly Display, pp. 33-37 (September, 2000), a three-color light-emitting method of arranging organic EL devices emitting lights corresponding to three primary colors (blue (B), green (G) and red (R)) of colors on a substrate, a white color method of separating white color emission by an organic EL device for white color emission to three colors through a color filter, and a color-converting method of converting blue color emission by an organic EL device for blue color emission to red (R) and green (G) through a fluorescent dye layer are known.

Further, by using in combination of a plurality of organic EL devices different in luminescent colors capable of obtaining by the above method, plane light sources of desired luminescent colors can be obtained. For example, a white emission light source of combining luminescence devices of blue and yellow luminescence devices, and a white emission light source of combining luminescence devices of blue, green and red are exemplified.

EXAMPLES Synthesis Example 1 Synthesis of Compound C-2 Below (Exemplified Compound 91)

To 2,2′-bipyridylsilane is added 1.1 equivalent weight of lithium tetramethyl piperidide in tetrahydrofuran at −40° C., and the mixture is subjected to reaction for 30 minutes. Chlorotriphenylsilane (1.2 equivalent weight) is added to the reaction mixture, followed by reaction at room temperature for 1 hour or so. The reaction mixture is hydrolyzed with a sodium hydrogencarbonate aqueous solution to obtain exemplified Compound 91 in a yield of 50%.

Synthesis Example 2 Synthesis of Compound C-1 Below (Exemplified Compound 116)

To 3-bromopyridine is added 1.1 equivalent weight of lithium diisopropylamide (LDA) in tetrahydrofuran at −70° C., and the mixture is subjected to reaction for 30 minutes. Dichlorodiphenylsilane (1.2 equivalent weight) is added to the reaction mixture, followed by reaction at room temperature for 1 hour or so. The reaction mixture is hydrolyzed with a sodium hydrogencarbonate aqueous solution to obtain Intermediate 1 in a yield of 40%. In toluene at II 0° C. in the presence of a Pd catalyst (palladium acetate/2-(di-t-butylphosphino)biphenyl), Intermediate 1 is reacted with phenylboronic acid to obtain exemplified Compound 116 in a yield of 70%.

Manufacture of Organic Electroluminescence Device: Comparative Example 1-1

A cleaned ITO substrate is put in a metallizing apparatus, copper phthalocyanine is deposited on the ITO substrate in a thickness of 10 nm, NPD ((N,N′-di-α-naphthyl-N,N′-diphenyl)benzidine) is deposited on the copper phthalocyanine film in a thickness of 40 nm (a hole transporting layer), Compound B-1 (shown below) and Compound A (shown below) in proportion of 12/88 (a mass ratio) are deposited thereon in a thickness of 30 nm (a light-emitting layer), BAlq (bis(2-methyl-8-quinolinolate)-4-phenylphenolate aluminum) is deposited thereon in a thickness of 30 nm, Alq (tris(8-hydroxyquinoline) aluminum complex) is deposited thereon in a thickness of 10 nm (an electron transporting layer), lithium fluoride is deposited thereon in a thickness of 3 nm, and aluminum is deposited thereon in a thickness of 60 nm. The obtained product is put in a glove box replaced with argon gas so as not to be in contact with air, and sealed with a stainless steel sealing can and a UV-curing type adhesive (XNR5516HV, manufactured by Nagase Chemtex Corporation) to obtain an organic electroluminescent device in Comparative Example 1. The obtained EL device is subjected to application of DC constant voltage with a source measure unit Model 2400 (manufactured by Toyo Corporation) to emit light. It is confirmed that the emission of phosphorescence originating in Compound B-1 is obtained.

Examples 1-1 to 1-20 and Comparative Examples 1-2 to 120

Devices are manufactured and evaluated in the same methods as in Comparative Example 1-1, except for changing the compounds used in the light-emitting layer and the electron transporting layer to the compounds shown in Table 1 below, respectively. It is confirmed that emission of phosphorescence originating in each light-emitting material used is obtained. The results obtained are shown in Table 1.

Evaluation of Performances of the Organic Electroluminescence Device: (a) External Quantum Efficiency

DC electric current is applied to each device for light emission with source measure unit Model 2400 (manufactured by Toyo Corporation). The luminance at that time is measured with a luminometer BM-8 (manufactured by Topcon Corporation). The light emission spectrum and emission wavelength are measured with a spectrum analyzer PMA-11 (manufactured by Hamamatsu Photonics K.K.). On the basis of these measurements, external quantum efficiency around 1,000 cd/m² of luminance is computed according to a luminance conversion method.

(b) Driving Voltage

DC voltage is applied to each device so as to reach luminance of 1,000 cd/m² for light emission, and the applied voltage is taken as the index of evaluation of driving voltage.

The results obtained of the above evaluations are shown in Table 1.

TABLE 1 Difference in Driving External Voltage Quantum between Light- Electron- Efficiency Comparative Emitting Transporting (relative Example 1-I Material Layer value) (ΔV) Comparative B-1 Alq 1.00 — Example 1-1 Example 1-1 B-1 C-1 1.34 −1.80 Example 1-2 B-1 C-2 1.20 −1.80 Example 1-3 B-1 C-3 1.29 −1.77 Example 1-4 B-1 C-4 1.12 −1.80 Example 1-5 B-1 C-5 1.15 −1.71 Comparative B-1 Exemplified 1.02 −0.44 Example 1-2 Compound 38 (D-1) in JP- A-2003-138251 Comparative B-1 Exemplified 0.61 +11.5 Example 1-3 Compound A-4 (D-2) in JP- A-2004-103463 Comparative B-1 Exemplified 0.75 +3.5 Example 1-4 Compound 34 (D-3) in JP- A-2003-138251 Comparative B-1 Exemplified 1.03 −0.52 Example 1-5 Compound 6 (D-4) in JP- A-2004-103463 Comparative B-2 Alq 1.12 −0.46 Example 1-6 Example 1-6 B-2 C-1 1.33 −2.27 Example 1-7 B-2 C-2 1.35 −2.25 Example 1-8 B-2 C-3 1.49 −2.21 Example 1-9 B-2 C-4 1.25 −2.29 Example 1-10 B-2 C-5 1.21 −1.97 Comparative B-2 D-1 1.23 −0.92 Example 1-7 Comparative B-2 D-2 1.28 +9.23 Example 1-8 Comparative B-2 D-3 0.82 +3.4 Example 1-9 Comparative B-2 D-4 1.09 −0.45 Example 1-10 Comparative B-3 Alq 1.22 −0.53 Example 1-11 Example 1-11 B-3 C-1 1.52 −2.35 Example 1-12 B-3 C-2 1.41 −2.38 Example 1-13 B-3 C-3 1.62 −2.31 Example 1-14 B-3 C-4 1.32 −2.35 Example 1-15 B-3 C-5 1.33 −2.10 Comparative B-3 D-1 1.26 −1.02 Example 1-12 Comparative B-3 D-2 1.30 +8.78 Example 1-13 Comparative B-3 D-3 0.89 +3.32 Example 1-14 Comparative B-3 D-4 1.15 −0.50 Example 1-15 Comparative B-4 Alq 1.04 −0.60 Example 1-16 Example 1-16 B-4 C-1 1.47 −2.40 Example 1-17 B-4 C-2 1.30 −1.92 Example 1-18 B-4 C-3 1.36 −2.11 Example 1-19 B-4 C-4 1.27 −2.05 Example 1-20 B-4 C-5 1.20 −1.91 Comparative B-4 D-1 0.99 +0.24 Example 1-17 Comparative B-4 D-2 0.61 +10.3 Example 1-18 Comparative B-4 D-3 0.92 +3.10 Example 1-19 Comparative B-4 D-4 1.16 −0.49 Example 1-20

As is apparent from the above results, the devices of the invention are high in external quantum efficiency and low in driving voltage as compared with the comparative devices.

Comparative Example 2-1

Similarly to Comparative Example 1-1, a cleaned ITO substrate is put in a metallizing apparatus, copper phthalocyanine is deposited on the ITO substrate in a thickness of 10 nm, NPD ((N,N′-di-α-naphthyl-N,N′-diphenyl)benzidine) is deposited on the copper phthalocyanine film in a thickness of 40 nm, Compound B-1 and Compound A in proportion of 12/88 (a mass ratio) are deposited thereon in a thickness of 30 nm to form a light-emitting layer. BAlq (bis(2-methyl-8-quinolinolate)-4-phenylphenolate aluminum) is deposited thereon in a thickness of 40 nm (an electron transporting layer), lithium fluoride is deposited thereon in a thickness of 3 nm, and aluminum is deposited thereon in a thickness of 60 nm to obtain a device. The obtained EL device is subjected to application of DC constant voltage with a source measure unit Model 2400 (manufactured by Toyo Corporation) to emit light. It is confirmed that the emission of phosphorescence originating in Compound B-1 is obtained.

Example 2-1

A device is manufactured in the same manner as in Comparative Example 2-1 except that the light-emitting layer in Comparative Example 2-1 (the layer formed by the deposition of Compound 131 and Compound A in proportion of 12/88 (a mass ratio) in a thickness of 30 nm) is changed to a layer obtained by depositing Compound B-1, Compound A and Compound C-1 in proportion of 12/75/13 (a mass ratio) in a thickness of 30 nm. As a result of evaluation in the same manner, it is confirmed that the emission of phosphorescence originating in Compound B-1 is obtained.

Examples 2-2 to 2-9, and Comparative Examples 2-2 to 2-9

EL devices are manufactured and evaluated in the same manner as in Example 2-1 except for changing the electron transporting host material in the light-emitting layer to the compounds shown in Table 2 below.

Comparative Example 2-4

An EL device is manufactured and evaluated in the same manner as in Comparative Example 2-1 except for changing the compound used in the light-emitting material to Compound B-2. The emission of phosphorescence originating in the used light-emitting material is obtained.

Example 2-4

A device is manufactured in the same manner as in Comparative Example 2-4 except that the light-emitting layer in Comparative Example 2-4 (the layer formed by the deposition of Compound B-2 and Compound A in proportion of 12/88 (a mass ratio) in a thickness of 30 nm) is changed to a layer obtained by depositing Compound B-2, Compound A and Compound C-1 in proportion of 12/75/13 (a mass ratio) in a thickness of 30 nm. As a result of evaluation in the same manner, it is confirmed that the emission of phosphorescence originating in Compound B-2 is obtained.

Examples 2-5 and 2-6, and Comparative Examples 2-5 and 2-6

EL devices are manufactured and evaluated in the same manner as in Example 2-1 except for changing the electron transporting host material in the light-emitting layer to the compounds shown in Table 2 below.

Comparative Example 2-7

An EL device is manufactured and evaluated in the same manner as in Comparative Example 2-1 except for changing the compound used in the light-emitting material to Compound B-3. The emission of phosphorescence originating in the used light-emitting material is obtained.

Example 2-7

A device is manufactured in the same manner as in Comparative Example 2-7 except that the light-emitting layer in Comparative Example 2-7 (the layer formed by the deposition of Compound 13-3 and Compound A in proportion of 12/88 (a mass ratio) in a thickness of 30 nm) is changed to a layer obtained by depositing Compound B-3, Compound A and Compound C-1 in proportion of 12/75/13 (a mass ratio) in a thickness of 30 nm. As a result of evaluation in the same manner, it is confirmed that the emission of phosphorescence originating in Compound B-3 is obtained.

Examples 2-8 and 2-9, and Comparative Examples 2-8 and 2-9

EL devices are manufactured and evaluated in the same manner as in Example 2-1 except for changing the electron transporting host material in the light-emitting layer to the compounds shown in Table 2 below.

The results of evaluations of the devices in Examples 2-1 to 2-9 and Comparative Examples 2-1 to 2-9 are shown in Table 2 below.

TABLE 2 Difference in Driving Hole-Transporting Electron-Transporting External Quantum Voltage between Light-Emitting Host Material in Host Material in Light Efficiency Comparative Example 1-I Material Light-Emitting Layer Emitting Layer (relative value) (ΔV) Comparative B-1 A — 1.00 — Example 2-1 Example 2-1 B-1 A C-1 1.19 −2.63 Example 2-2 B-1 A C-3 1.17 −2.59 Example 2-3 B-1 A C-5 1.16 −2.40 Comparative B-1 A D-3 0.26 +8.89 Example 2-2 Comparative B-1 A D-4 0.68 +2.30 Example 2-3 Comparative B-2 A — 1.10 −0.31 Example 2-4 Example 2-4 B-2 A C-1 1.40 −2.78 Example 2-5 B-2 A C-3 1.43 −2.81 Example 2-6 B-2 A C-5 1.37 −2.71 Comparative B-2 A D-3 0.30 +8.56 Example 2-5 Comparative B-2 A D-4 0.72 +2.14 Example 2-6 Comparative B-3 A — 1.24 −0.48 Example 2-7 Example 2-7 B-3 A C-1 1.58 −2.85 Example 2-8 B-3 A C-3 1.60 −2.94 Example 2-9 B-3 A C-5 1.55 −2.88 Comparative B-3 A D-3 0.33 +8.11 Example 2-8 Comparative B-3 A D-4 0.77 +2.05 Example 2-9

As is apparent from the above results, the devices of the invention are high in external quantum efficiency and low in driving voltage as compared with the comparative devices.

Comparative Example 3-1

Similarly to Comparative Example 2-1, a cleaned ITO substrate is put in a metallizing apparatus, copper phthalocyanine is deposited on the ITO substrate in a thickness of 10 nm NPD ((N,N′-di-α-naphthyl-N,N′-diphenyl)benzidine) is deposited on the copper phthalocyanine film in a thickness of 40 nm, Compound B-4 and Compound A in proportion of 12/88 (a mass ratio) are deposited thereon in a thickness of 20 nm to form a light-emitting layer. BAlq (bis(2-methyl-8-quinolinolate)-4-phenylphenolate aluminum) is deposited thereon in a thickness of 40 nm (an electron transporting layer), lithium fluoride is deposited thereon in a thickness of 3 mm, and aluminum is deposited thereon in a thickness of 60 mm to obtain a device. The obtained EL device is subjected to application of DC constant voltage with a source measure unit Model 2400 (manufactured by Toyo Corporation) to emit light. It is confirmed that the emission of phosphorescence originating in Compound B-5 is obtained.

Example 3-1

A device is manufactured in the same manner as in Comparative Example 3-1 except that the light-emitting layer in Comparative Example 3-1 (the layer formed by the deposition of Compound B-5 and Compound A in proportion of 12/88 (a mass ratio) in a thickness of 30 nm) is changed to a layer obtained by depositing Compound B-5, Compound A and Compound C-1 in proportion of 12/75/13 (a mass ratio) in a thickness of 30 nm. As a result of evaluation in the same manner, it is confirmed that the emission of phosphorescence originating in Compound B-5 is obtained.

Examples 3-2 and 3-3, And Comparative Examples 3-2 and 3-3

EL devices are manufactured and evaluated in the same manner as in Example 3-1 except for changing the electron transporting host material in the light-emitting layer to the compounds shown in Table 3 below.

Comparative Example 3-4

An EL device is manufactured and evaluated in the same manner as in Comparative Example 3-1 except for changing the compound used in the light-emitting material to Compound B-4. The emission of phosphorescence originating in the used light-emitting material is obtained.

Example 3-4

A device is manufactured in the same manner as in Comparative Example 3-4 except that the light-emitting layer in Comparative Example 3-4 (the layer formed by the deposition of Compound B-4 and Compound A in proportion of 12188 (a mass ratio) in a thickness of 30 nm) is changed to a layer obtained by depositing Compound B-4, Compound A and Compound C-1 in proportion of 12/75/13 (a mass ratio) in a thickness of 30 nm. As a result of evaluation in the same manner, it is confirmed that the emission of phosphorescence originating in Compound B-4 is obtained.

Examples 3-5 and 3-6, and Comparative Examples 3-5 and 3-6

EL devices are manufactured and evaluated in the same manner as in Example except for changing the electron transporting host material in the light-emitting layer to the compounds shown in Table 3 below.

The results of evaluations of the devices in Examples 3-1 to 3-6 and Comparative Examples 3-1 to 3-6 are shown in Table 3 below.

TABLE 3 Hole- Electron- Difference Transporting Transporting in Driving Host Host External Voltage Material Material Quantum between Light- in Light- in Light Efficiency Comparative Emitting Emitting Emitting (relative Example 1-1 Material Layer Layer value) (ΔV) Comparative B-5 A — 1.00 — Example 3-1 Example 3-1 B-5 A C-1 1.14 −1.76 Example 3-2 B-5 A C-3 1.15 −1.44 Example 3-3 B-5 A C-5 1.19 −1.40 Comparative B-5 A D-3 0.37 +6.43 Example 3-2 Comparative B-5 A D-4 0.87 +2.10 Example 3-3 Comparative B-4 A — 1.03 −0.05 Example 3-4 Example 3-4 B-4 A C-1 1.35 −1.93 Example 3-5 B-4 A C-3 1.28 −1.60 Example 3-6 B-4 A C-5 1.31 −1.81 Comparative B-4 A D-3 0.40 +6.03 Example 3-5 Comparative B-4 A D-4 0.89 +1.98 Example 3-6

As is apparent from the above results, the devices of the invention are high in external quantum efficiency and low in driving voltage as compared with the comparative devices.

Comparative Example 4-1

A cleaned ITO substrate is put in a metallizing apparatus, copper phthalocyanine is deposited on the ITO substrate in a thickness of 10 nm, NPD ((N,N′-di-α-naphthyl-N,N′-diphenyl)benzidine) is deposited on the copper phthalocyanine film in a thickness of 40 nm, Compound B-6 (shown below) and CBP (4,4′-di(9-carbazoyl)biphenyl) (shown below), and Compound D-3 in proportion of 12/75/13 (a mass ratio) are deposited thereon in a thickness of 15 nm (a light-emitting layer), BAlq (bis(2-methyl-5-quinolinolate)-4-phenylphenolate aluminum) is deposited thereon in a thickness of 40 nm (an electron transporting layer), lithium fluoride is deposited thereon in a thickness of 3 nm, and aluminum is deposited thereon in a thickness of 60 nm to obtain a device. The obtained EL device is subjected to application of DC constant voltage with a source measure unit Model 2400 (manufactured by Toyo Corporation) to emit light. It is confirmed that the emission of phosphorescence originating in Compound B-3 is obtained.

Examples 4-1 to 4-3, and Comparative Example 4-2

Devices are manufactured and evaluated in the same methods as in Comparative Example 41, except for changing the compounds used in the electron transporting host material in the light-emitting layer to the compounds shown in Table 4 below. It is confirmed that emission of phosphorescence originating in each light-emitting material used is obtained. The results obtained are shown in Table 4.

TABLE 4 Hole- Electron- Difference Transporting Transporting in Driving Host Host External Voltage Material Material Quantum between Light- in Light- in Light Efficiency Comparative Emitting Emitting Emitting (relative Example 1-1 Material Layer Layer value) (ΔV) Comparative B-6 CBP D-3 1.00 — Example 4-1 Comparative B-6 CBP D-4 1.56 −1.10 Example 4-2 Example 4-1 B-6 CBP C-1 2.43 −1.89 Example 4-2 B-6 CBP C-3 2.58 −1.56 Example 4-3 B-6 CBP C-5 2.61 −1.79

As is apparent from the above results, the devices of the invention are high in external quantum efficiency and low in driving voltage as compared with the comparative devices.

Comparative Example 5-1

A cleaned ITO substrate is put in a metallizing apparatus, copper phthalocyanine is deposited on the ITO substrate in a thickness of 10 nm, NPD ((N,N′-di-α-naphthyl-N,N-diphenylbenzidine) is deposited on the copper phthalocyanine film in a thickness of 40 nm, Rubrene (shown below) and Compound D-2 in proportion of 3/97 (a mass ratio) are deposited thereon in a thickness of 10 nm (a light-emitting layer), BAlq (bis(2-methyl-8-quinolinolate)-4-phenylphenolate aluminum) (bis(6-hydroxyquinoline)-(4-phenylphenol) Al complex salt) is deposited thereon in a thickness of 40 nm (an electron transporting layer), lithium fluoride is deposited thereon in a thickness of 3 nm, and aluminum is deposited thereon in a thickness of 60 nm to obtain a device. The obtained EL device is subjected to application of DC constant voltage with a source measure unit Model 2400 (manufactured by Toyo Corporation) to emit light. It is confirmed that the emission of phosphorescence originating in Rubrene is obtained.

Examples 5-1 to 5-3

Devices are manufactured and evaluated in the same methods as in Comparative Example 5-1, except for changing the compound used as the host material in the light-emitting layer to the compounds shown in Table 5 below. Emission of phosphorescence originating in each light-emitting material used is obtained. The results obtained are shown in Table 5.

TABLE 5 Light-Emitting External Difference Layer Quantum in Dr Efficiency Between (relative Example 4-1 value) (ΔV) Comparative Rubrene D-3 1.00 — Example 5-1 Example 5-1 Rubrene C-1 2.32 −2.87 Example 5-2 Rubrene C-3 2.10 −2.66 Example 5-3 Rubrene C-5 2.01 −2.60

As is apparent from the above Examples, by the use of the compounds in the invention, external quantum efficiency of organic electroluminescence devices can be improved and driving voltage can be lowered.

The organic electroluminescence device in the invention contains at least one silicon-linking type nitrogen-containing heterocyclic compound (which is used in the same definition with “the compound of the invention” in the specification of the invention) represented by any of formulae (I) to (V) in the organic layer. By containing the compound, the invention can provide an organic electroluminescence device having high luminous efficiency (e.g., external quantum efficiency), and excellent in durability (which is used in the same definition with “the device of the invention” in the specification of the invention). Further, by the use of the compound having a special structure, the invention can provide an organic electroluminescence device capable of emitting light in high external quantum efficiency in a blue region and at the same time excellent in durability.

The entire disclosure of each and every foreign patent application from which the benefit of foreign priority has been claimed in the present application is incorporated herein by reference, as if fully set forth. 

1. An organic electroluminescence device comprising: an anode; a cathode; and at least one organic layer, wherein the at least one organic layer comprises a light-emitting layer being provided between the anode and the cathode and containing at least one light-emitting material, and the at least one organic layer contains at least one compound represented by formula (I):

wherein each of A¹¹, A¹², A¹³, A¹⁴ and A¹⁵ represents an N atom or C—R¹¹, and the number of N atoms represented by A¹¹ to A¹⁵ is an integer of 1 or 2; R¹¹ represents a hydrogen atom or a substituent, and at least one of R¹¹ represents an aryl group or an aromatic heterocyclic group; when a plurality of partial structures represented by the following formula (I-a) are present, each partial structure (I-a) may be the same with or different from every other (I-a); Q¹¹ represents a monocyclic aryl group or an aromatic heterocyclic group, and each Q¹¹ may be the same with or different from every other Q¹¹; R¹² represents an alkyl group, and each R¹² may be the same with or different from every other R¹²; and each of n, m and l represents an integer of from 0 to 4, provided that n is an integer of 1 or more, n+m is an integer of 2 or more, and n+m+l is 4:


2. The organic electroluminescence device as claimed in claim 1, wherein the compound represented by formula (I) is a compound represented by formula (II):

wherein each of A²¹, A²², A²³, A²⁴ and A²⁵ represents an N atom or C—R²¹, and the number of N atom represented by A²¹ to A²⁵ is 1; R²¹ represents a hydrogen atom or a substituent, and at least one of R²¹ represents an aryl group or an aromatic heterocyclic group; when a plurality of partial structures represented by the following formula (II-a) are present, each partial structure (II-a) may be the same with or different from every other (II-a); Q²¹ represents a monocyclic aryl group or an aromatic heterocyclic group, and each Q²¹ may be the same with or different from every other Q²¹; R²² represents an alkyl group, and each R²² may be the same with or different from every other R²²; and each of n, m and l represents an integer of from 0 to 4, provided that n is an integer of 1 or more, n+m is an integer of 2 or more, and n+m+l is 4:


3. The organic electroluminescence device as claimed in claim 2, wherein the compound represented by formula (II) is a compound represented by formula (III):

wherein R³¹ represents a hydrogen atom or a substituent, and at least one of R³¹ represents an aryl group or an aromatic heterocyclic group; when a plurality of partial structures represented by the following formula (III-a) are present, each partial structure (III-a) may be the same with or different from every other (II-a); Q³¹ represents a monocyclic aryl group or an aromatic heterocyclic group, and each Q³¹ may be the same with or different from every other Q³¹; R³² represents an alkyl group, and each R³² may be the same with or different from every other R³²; and each of n, m and l represents an integer of from 0 to 4, provided that n is an integer of 1 or more, n+m is an integer of 2 or more, and n+m+l is 4:


4. The organic electroluminescence device as claimed in claim 2, wherein the compound represented by formula (II) is a compound represented by formula (IV):

wherein R⁴¹ represents a hydrogen atom or a substituent, and at least one of R⁴¹ represents an aryl group or an aromatic heterocyclic group; when a plurality of partial structures represented by the following formula (IV-a) are present, each partial structure (IV-a) may be the same with or different from every other (IV-a); Q⁴¹ represents a monocyclic aryl group or an aromatic heterocyclic group, and each Q⁴¹ may be the same with or different from every other Q⁴¹; R⁴² represents an alkyl group, and each R⁴² may be the same with or different from every other R⁴²; and each of n, m and l represents an integer of from 0 to 4, provided that n is an integer of 1 or more, n+m is an integer of 2 or more, and n+m+l is 4:


5. The organic electroluminescence device as claimed in claim 2, wherein the compound represented by formula (II) is a compound represented by formula (V):

wherein R⁵¹ represents a hydrogen atom or a substituent, and at least one of R⁵¹ represents an aryl group or an aromatic heterocyclic group; when a plurality of partial structures represented by the following formula (V-a) are present, each partial structure (V-a) may be the same with or different from every other (V-a); Q⁵¹ represents a monocyclic aryl group or an aromatic heterocyclic group, and each Q⁵¹ may be the same with or different from every other Q⁵¹; R⁵² represents an alkyl group, and each R² may be the same with or different from every other R⁵²; and each of n, m and l represents an integer of from 0 to 4, provided that n is an integer of 1 or more, n+m is an integer of 2 or more, and n+m+l is 4;


6. The organic electroluminescence device as claimed in claim 1, wherein the compound represented by formula (I) has a glass transition temperature of 130° C. or more and 450° C. or less.
 7. The organic electroluminescence device as claimed in claim 1, wherein the compound represented by formula (I) has a lowest excitation triplet energy level of 65 kcal/mol (272.35 kJ/mol) or more and 95 kcal/mol (398.05 kJ/mol) or less.
 8. The organic electroluminescence device as claimed in claim 1, wherein the at least one light-emitting material comprises a phosphorescent material.
 9. The organic electroluminescence device as claimed in claim 8, wherein the phosphorescent material is an iridium complex or a platinum complex.
 10. The organic electroluminescence device as claimed in claim 9, wherein the platinum complex is a platinum complex represented by formula (C-1):

wherein each of Q¹, Q², Q³ and Q⁴ independently represents a ligand to coordinate to Pt; and each of L¹, L² and L³ independently represents a single bond or a divalent linking group.
 11. The organic electroluminescence device as claimed in claim 1, wherein the light-emitting layer contains the compound represented by formula (I).
 12. The organic electroluminescence device as claimed in claim 1, wherein the at least one organic layer further comprises at least one electron transporting layer being provided between the light-emitting layer and the cathode, and the at least one electron transporting layer contains the compound represented by formula (I). 